Página 1 dos resultados de 2183 itens digitais encontrados em 0.006 segundos

Alternative mating tactics in dimorphic males of the harvestman Longiperna concolor (Arachnida: Opiliones)

ZATZ, Camila; WERNECK, Rachel M.; MACIAS-ORDONEZ, Rogelio; MACHADO, Glauco
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.98%
Intense male-male competition for females may drive the evolution of male morphological dimorphism, which is frequently associated with alternative mating tactics. Using modern techniques for the detection of discontinuous allometries, we describe male dimorphism in the Neotropical harvestman Longiperna concolor, the males of which use their elongated, sexually dimorphic legs IV in fights for the possession of territories where females lay eggs. We also tested three predictions related to the existence of alternative mating tactics: (1) if individuals with relatively longer legs IV (majors) are more likely to monopolize access to reproductive resources, they are expected to remain close to stable groups of females more than individuals with relatively shorter legs IV (minors) do; (2) if minors achieve fertilization by moving between territories, they are expected to be less faithful to specific sites; and (3) majors should be observed in aggressive interactions more often. We individually marked all the individuals from a population of Longiperna during the reproductive season and recorded the location of each sighting for males and females as well as the identity of males involved in fights. Majors were more likely to have harems...

Do individuals in better condition survive for longer? Field survival estimates according to male alternative reproductive tactics and sex

MUNGUIA-STEYER, R.; CORDOBA-AGUILAR, A.; ROMO-BELTRAN, A.
Fonte: WILEY-BLACKWELL PUBLISHING, INC Publicador: WILEY-BLACKWELL PUBLISHING, INC
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.98%
There is a gap in terms of the supposed survival differences recorded in the field according to individual condition. This is partly due to our inability to assess survival in the wild. Here we applied modern statistical techniques to field-gathered data in two damselfly species whose males practice alternative reproductive tactics (ARTs) and whose indicators of condition in both sexes are known. In Paraphlebia zoe, there are two ART: a larger black-winged (BW) male which defends mating territories and a smaller hyaline-winged (HW) male that usually acts as a satellite. In this species, condition in both morphs is correlated with body size. In Calopteryx haemorrhoidalis, males follow tactics according to their condition with males in better condition practicing a territorial ART. In addition, in this species, condition correlates positively with wing pigmentation in both sexes. Our prediction for both species was that males practicing the territorial tactic will survive less longer than males using a nonterritorial tactic, and larger or more pigmented animals will survive for longer. In P. zoe, BW males survived less than females but did not differ from HW males, and not necessarily larger individuals survived for longer. In fact, size affected survival but only when group identity was analysed...

Stirring, charging, and picking: hunting tactics of potamotrygonid rays in the upper Paraná River

Garrone-Neto, Domingos; Sazima, Ivan
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: 113-116
ENG
Relevância na Pesquisa
36.98%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); As táticas de caça de raias potamotrigonídeas permanecem sem registro sob condições naturais. Três táticas de forrageamento são aqui descritas para Potamotrygon falkneri e P. motoro, com base em observações subaquáticas no curso superior do rio Paraná. Ambas as espécies apresentaram comportamento semelhante. A tática mais comum foi a de ondular as margens do disco próximo ao, ou no, fundo e assim perturbando o substrato e revelando presas abrigadas. Outra tática foi a de investir sobre presas concentradas no raso. A tática menos frequente foi a de apanhar presas aderidas ao substrato. A primeira tática é comum em diversas espécies de raias marinhas da família Dasyatidae, ao passo que as outras duas (em particular apanhar presas em substratos acima da superfície da água) podem estar restritas a Potamotrygonidae.; Hunting tactics of potamotrygonid freshwater rays remain unreported under natural conditions. Three main foraging tactics of Potamotrygon falkneri and P. motoro are described here based on underwater observations in the upper Paraná River. Both species displayed similar behaviors. The most common tactic was to undulate the disc margins close to...

Stirring, charging, and picking: hunting tactics of potamotrygonid rays in the upper Paraná River

Garrone-Neto,Domingos; Sazima,Ivan
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2009 EN
Relevância na Pesquisa
36.98%
Hunting tactics of potamotrygonid freshwater rays remain unreported under natural conditions. Three main foraging tactics of Potamotrygon falkneri and P. motoro are described here based on underwater observations in the upper Paraná River. Both species displayed similar behaviors. The most common tactic was to undulate the disc margins close to, or on, the bottom and thus stirring the substrate and uncovering hidden preys. Another tactic was to charge upon prey concentrated in the shallows. The least common tactic was to pick out prey adhered to the substrate. The first tactic is widespread in several species of marine rays in the Dasyatidae, whereas the remainder (especially picking up prey on substrata above water surface) may be restricted to the Potamotrygonidae.

Coordinated feeding behavior of the Guiana dolphin, Sotalia guianensis (Cetacea: Delphinidae), in southeastern Brazil: a comparison between populations

Oliveira,Elaine C. da S.; Tardin,Rodrigo H.; Poletto,Fabiana R.; Simão,Sheila M.
Fonte: Sociedade Brasileira de Zoologia Publicador: Sociedade Brasileira de Zoologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
27.34%
The coordinated feeding tactics used by delphinids are influenced by differences in the distribution of prey species, season, and opportunities for social learning. In the present study, we compared the coordinated feeding behavior of two populations of the Guiana dolphin, Sotalia guianensis, in southeastern Brazil, and how these feeding tactics vary seasonality and in the presence of calves. We observed eight types of coordinated feeding tactics, which differed in frequency and in the mean number of individuals engaged in them, and between both areas. Feeding tactics used to herd and capture prey were the most frequent and engaged a greater number of individuals, suggesting that these tactics are better for capturing fish that gather in larger schools. Furthermore, the seasons influenced the occurrence of different prey items, which in turn modified the feeding tactics of the dolphins. In the Ilha Grande Bay we observed that bouts lasted longer and larger groups engaged in the feeding tactics, which may be associated with the seasonal spawning of larger schooling fish such as Sardinella brasiliensis (Steindachner, 1879) (Teleostei: Clupeidae). However, in the Sepetiba Bay, we observed longer feeding bouts and a smaller number of individuals engaged in the feeding tactics during autumn-winter. This may be associated with the fact that the most abundant prey species...

Behavioural Thermoregulatory Tactics in Lacustrine Brook Charr, Salvelinus fontinalis

Bertolo, Andrea; Pépino, Marc; Adams, Julie; Magnan, Pierre
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 07/04/2011 EN
Relevância na Pesquisa
27.28%
The need to vary body temperature to optimize physiological processes can lead to thermoregulatory behaviours, particularly in ectotherms. Despite some evidence of within-population phenotypic variation in thermal behaviour, the occurrence of alternative tactics of this behaviour is rarely explicitly considered when studying natural populations. The main objective of this study was to determine whether different thermal tactics exist among individuals of the same population. We studied the behavioural thermoregulation of 33 adult brook charr in a stratified lake using thermo-sensitive radio transmitters that measured hourly individual temperature over one month. The observed behavioural thermoregulatory patterns were consistent between years and suggest the existence of four tactics: two “warm” tactics with both crepuscular and finer periodicities, with or without a diel periodicity, and two “cool” tactics, with or without a diel periodicity. Telemetry data support the above findings by showing that the different tactics are associated with different patterns of diel horizontal movements. Taken together, our results show a clear spatio-temporal segregation of individuals displaying different tactics, suggesting a reduction of niche overlap. To our knowledge...

Aggressive Transition between Alternative Male Social Tactics in a Long-Lived Australian Dragon (Physignathus lesueurii) Living at High Density

Baird, Troy A.; Baird, Teresa D.; Shine, Richard
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 08/08/2012 EN
Relevância na Pesquisa
27.24%
Theory predicts the evolution of alternative male social tactics when intense competition coupled with the superior competitive ability of some individuals limits access to reproductive opportunities by others. How selection has shaped alternative social tactics may be especially interesting in long-lived species where size among sexually mature males varies markedly. We conducted experimental studies on long-lived eastern Australian water dragons living where competition was intense to test the hypotheses that mature males adopt alternative social tactics that are plastic, and that large size and body condition determine resource-holding potential. Approximately one-half of mature males (N = 14) defended territories using high rates of patrol and advertisement display, whereas 16 smaller mature males having lower body condition indices utilized non-territorial social tactics. Although territorial males were larger in absolute size and head dimensions, their heads were not allometrically larger. Territorial males advertised very frequently using displays involving stereotypical movements of the head and dewlap. More aggressive displays were given infrequently during baseline social conditions, but increased during periods of social instability. Female home ranges overlapped those of several territorial and non-territorial males...

Psychopathy and self-monitoring : additive and interactive effects on self-presentation tactics /

Worth, Narnia.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
Relevância na Pesquisa
27.34%
The purpose of this study was to determine the relative contributions of psychopathy and self-monitoring to the prediction of self-presentation tactics (behaviours that individuals use to manipulate their self-image). Psychopathy is composed of two main factors: Factor 1, which includes manipulativeness and shallow affect, and Factor 2, which includes irresponsibility and anti-social behaviours. Self-monitoring is a personality trait that distinguishes between those who adapt their behaviour to fit different social situations (high self-monitors) and those who behave as they feel regardless of social expectations (low selfmonitors). It was hypothesized that self-monitoring would moderate the relationship between psychopathy and self-presentation tactics. One hundred and forty-nine university students completed the Self-Monitoring Scale (Snyder, 1974), the Self-Report Psychopathy Scale - Version III (Paulhus et aI., in press), the Self-Presentation Tactics scale (Lee, S., et aI., 1999), the HEXACO-PI (a measure ofthe six major factors of personality; Lee, K., & Ashton, 2004), and six scenarios that were created as a supplementary measure of the selfpresentation tactics. Results of the hierarchical multiple regression analyses showed that self-monitoring did moderate the relationship between psychopathy and three of the selfpresentation tactics: apologies...

Bargaining tactics and strategy in a Government/Contractor bilateral monopoly

Van Veen, Dennis Gerard.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: ix, 161 p.
EN_US
Relevância na Pesquisa
36.98%
Approved for public release; distribution is unlimited; The purpose of this research is to examine potential bargaining strategies and tactics which might be used to respond to an offer perceived as unfair or unreasonable from a sole source offeror. Initially, a sole source offeror normally has considerable bargaining leverage over the Government. Pricing data needed to properly evaluate the seller's quotation may be incomplete, inaccurate or unavailable. Urgent and compelling need may require accelerating the procurement process. Using bargaining theory and the classic economic paradigm of bilateral monopoly as a foundation for the research, potential bargaining strategies and tactics were evaluated through a survey of 62 Department of Defense contracting specialists. A primary conclusion of the research is that attaining a bargaining agreement that reflects a fair and reasonable price under bilateral monopoly conditions is not possible unless the Government possesses adequate information to accurately assess the fairness and reasonableness of the offered price.; http://www.archive.org/details/bargainingtactic00vanv; Lieutenant, United States Navy

Submarine approach and attack tactics: simulation and analysis

Bakos, George K.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 49 p.
EN_US
Relevância na Pesquisa
36.84%
The purpose of this thesis is to assess the probability of a diesel submarine's successful attack when using bearings-only Target Motion Analysis (TMA) while approaching a surface target. Four different approach tactics are examined: POINT LEAD - POINT, POINT - LEAD - LAG, POINT - LAG - LEAD and POINT - LAG - POINT. The submarine approach problem addressed in this thesis was solved using Monte Carlo simulation. Each simulation run includes 1,000 replications for each combination of submarine speed, target speed and tactic. Each replication starts by specifying initial conditions for the target and submarine. Then the submarine's approach phase is simulated, consisting of three legs (TMA maneuvers) during which the submarine computes the target speed, course and range. The simulation continues with the attack phase, where the submarine decides if a torpedo can reach the target. Finally the success or failure of the attack is determined. The number of successful attacks in each simulation is a measure of effectiveness of the particular tactic. The simulation shows that the tactic which maximizes the probability of successful attack is Point-Lead-Point, but possibly other considerations not captured in the simulation model would recommend a different tactic choice. Due to the variety' of arbitrar' tactical assumptions...

General use of UAS in EW environment--EW concepts and tactics for single or multiple UAS over the net-centric battlefield

Erdemli, Mustafa Gokhan.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xx, 223 p. : ill. ;
Relevância na Pesquisa
36.98%
Approved for public release, distribution unlimited; With the development of technology, Electronic Warfare has been increasing for decades its importance in modern battles. It can even be referred to as the heart of today's net-centric battlefield. Unmanned Aerial Systems are gaining more importance every single day. Nations are working on more complex and more effective UAS in order to accomplish missions that are very difficult, or even impossible for manned aircraft. Electronic Warfare missions are often dangerous and risky. Mounting Electronic Warfare equipment on a UAS and using it to conduct the EW mission is the most rational solution, since it does not endanger human life. This thesis will examine the possible ways in which UAS can be paired with EW equipment. These two technologies can be integrated into a single mission over the net-centric battlefield. Furthermore, this thesis will try to explain the concepts and tactics required to use these integrated technologies more effectively. At the end of the thesis, a scenario will be run to help the reader understand the applicability of these tactics in the real environment.; Turkish Air Force author.

An analysis of small navy tactics using a modified Hughes' Salvo Model

Tiah, Yao Ming
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xxii, 87 p. : ill. (some col.) ;
Relevância na Pesquisa
36.84%
Approved for public release; distribution is unlimited; This thesis develops a modified version of Hughes' Salvo Model and employs it to analyze the tactical disposition (concentration or dispersion) of a small, but modern, navy whose adversary is numerically superior but technologicaly inferior. It also identifies tactical factors and develops insights that are critical to the success of small navies when fighting outnumbered. Quantitative results indicate that the smaller navy must fight dispersed and win by outscouting the enemy and attacking him effectively first. This requires a superior scouting capability, effective command, control, and communications (C3), and the ability to deliver sufficient striking power. To ensure the delivery of sufficient striking power, a small navy must put greater emphasis on offensive firepower to compensate for small force size. To be successful in battle, small navies must show initiative, and be willing to implement bold tactics. These attributes have been demonstrated by small, but successful, naval forces in the history of naval warfare. In addition, innovative tactical thinking can allow small navies to take advantage of useful tactical phenomena like the "missile-sump-effect" and to design the most appropriate type of combat craft for their respective operating environments.; Outstanding Thesis; Singapore DSO National Laboratories author (civilian).

Exploring naval tactics with UAVs in an island complex using agent-based simulation

Lalis, Vasileios.
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xxii, 63 p. : ill. ;
Relevância na Pesquisa
37.08%
The benefits of Unmanned Aerial Vehicles (UAV) at sea are undisputed. The amount and speed of the incoming information from a UAV, combined with its maneuverability and "time-on-task" capability, are assets to any navy. For the Greek Navy, the main local operation area is the Aegean and Ionian Sea. As Greece lies between three continents (Europe, Asia, Africa), there is a great deal of sea traffic and potential illegal activities, such as smuggling, exploitation of illegal immigrants, and possible terrorist activity. The scope of this study is to explore naval tactics with UAVs in an island complex using Agent-Based Simulation. MANA (Map Aware Non-uniform Automata) software, used in this study, provides a visual and realistic background to conduct simulations of real operations involving many different entities. This thesis demonstrates that this type of software can rapidly produce, explore and check simulated naval tactics before actual implementation. It also shows how the UAV's technology plays a key role in a search and detection operation, whereas the enemy must rely mostly on his tactics.; Hellenic Navy author.

A view from the teeth in the war of the flea an analysis of U.S. Army tactics in Iraq

Faulkner, Dennis W.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xii, 81 p. ;
Relevância na Pesquisa
37.15%
This thesis examines the tactics used by the U.S. Army during 2004-2005 in Iraq. The central aim of this study is to understand why the Army chose tactics that were ill-suited to the conflict and why it took nearly three years to adapt to conditions in Iraq. The Army applied doctrine that was familiar to it as an institution and was reluctant to accept tactics and changes in conduct that might violate its culture and doctrine. Tactics employed by many Army units were more akin to a counter-terror campaign rather than a counterinsurgency. A counter-terror operation is focused on the defeat of the enemy directly through kinetic means while a counterinsurgency focuses on defeating the enemy indirectly by interrupting the insurgents' ideology and base of support. The greatest inhibitors to innovation in Iraq were commanders who resisted innovation because they did not understand the nature of the conflict in which they were engaged. They also were restricted by traditional Army culture.; US Army (USA) author.

Measures of effectiveness Israeli counterterrorism strategies and tactics during the al-Aqsa Intifada

Maye, Diane L.
Fonte: Monterey California. Naval Postgraduate School Publicador: Monterey California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xii, 79 p. : col. ill. ;
Relevância na Pesquisa
37.08%
On September 28, 2000, Israel's Likud party leader, Ariel Sharon, visited the Temple Mount in the Old City of Jerusalem. His visit spawned the al-Aqsa Intifada, a period of significant Palestinian resistance that has never "officially" ended, and whose reverberations continue to be felt to this day. This thesis assesses Israel's counter-terror strategies and tactics during the al-Aqsa Intifada in light of established scholarly measures of effectiveness. It focuses on specific Israeli actions aimed at countering Palestinian resistance. These include: targeted assassinations, home demolitions, collective punishments, border controls, administrative detention, controls on terrorist financing and technological advances. It assesses those tactics, year by year, to determine whether or not there was a correlation between the tactics and the number of anti-Israeli terrorist incidents. This tactical analysis provides a basis on which to appraise Israeli counter-terror strategy and its long-term effectiveness. It concludes with a consideration of the long-term implications of the Israeli's experience.

Coordinated feeding tactics of the Guiana dolphin, Sotalia guianensis (Cetacea: Delphinidae), in Ilha Grande Bay, Rio de Janeiro, Brazil

Tardin,Rodrigo H. O.; Especie,Mariana A.; Nery,Mariana F.; D'Azeredo,Felipe T.; Simão,Sheila M.
Fonte: Sociedade Brasileira de Zoologia Publicador: Sociedade Brasileira de Zoologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2011 EN
Relevância na Pesquisa
27.24%
Differences in distribution, prey species, season and social learning opportunities influence the feeding tactics used by marine mammals. Here, we analyze the coordinated feeding behavior of the Guiana dolphin, Sotalia guianensis (Van Bénéden, 1864, Delphinidae) and its relation to seasonality and the presence of calves. In a total of 201 feeding bouts, we observed four types of coordinated feeding tactics, which differed in frequency and in mean number of engaged individuals. Tactics in which dolphins used their bodies to herd and capture prey were the most frequent, presenting a higher frequency and engaging a higher number of individuals, suggesting that these tactics are better for capturing fishes which form larger schools. Furthermore, the seasons influenced the feeding behavior used by dolphins. During spring-summer, a longer duration of bouts and a larger number of individuals engaged in the feeding tactics was observed, which may be related to the seasonal spawning of larger schooling fish, such as Sardinella brasiliensis (Steindachner, 1879). Calves were present in 95% of all coordinated feeding tactic occurrences. This study indicates a complete preference of dolphins for coordinating their actions to capture prey and for the first time reports the presence of calves in the coordinated tactics and jumps. This broadens the current knowledge of the Guiana dolphin feeding tactics.

Translocation tactics: A framework to support the IUCN Guidelines for wildlife translocations and improve the quality of applied methods

Batson, William; Gordon, Iain; Fletcher, Donald; Manning, Adrian
Fonte: British Ecological Society Publicador: British Ecological Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.34%
Translocation is a popular conservation tool, but the outcomes are variable. Many tactics can be used to improve the probability of success, but a comprehensive summary of these does not exist. This increases the risk that valuable tactics will be overlooked, and inhibits effective communication. We assess the diversity of 'translocation tactics' used in mammal and bird translocations, by reviewing the IUCN/SSC Guidelines for Reintroduction and other Conservation Translocations, 195 peer-reviewed articles and 73 case studies from the IUCN/SSC Global Reintroduction Perspectives Series. We recorded descriptions of every technique used to influence the post-release performance of translocated wildlife. We developed the Translocation Tactics Classification System (TTCS) which defines a collection of 30 tactics and organize them into an ecologically relevant framework. We also assess the occurrence of tactics within the Guidelines, the primary literature and the case studies to evaluate how tactics are communicated within these mediums. Our results indicate that the Guidelines are a valuable resource, but do not exhaustively cover tactics, and that detailed methodological accounts are rarely made publicly accessible. This highlights the need to develop context-specific resources to support the Guidelines...

A estratégia como prática social nas organizações: articulações entre representações sociais, estratégias e táticas cotidianas; La estrategia como práctica social en las organizaciones: articulaciones entre representaciones sociales, estrategias y tácticas cotidianas; Strategy as social practice in organizations: links between social representations, strategies and everyday tactics

Silva, Alfredo Rodrigues Leite da; Carrieri, Alexandre de Pádua; Junquilho, Gelson Silva
Fonte: Universidade de São Paulo. Faculdade de Economia, Administração e Contabilidade Publicador: Universidade de São Paulo. Faculdade de Economia, Administração e Contabilidade
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Artigo Avaliado pelos Pares Formato: application/pdf
Publicado em 01/06/2011 POR
Relevância na Pesquisa
36.84%
O objetivo neste artigo é propor um caminho teórico-metodológico que permita o estudo do fazer estratégia em organizações, a partir de uma abordagem inserida na visão da estratégia como prática social, na qual os contextos - macro e microssociais -, bem como suas delimitações, são manifestados pelos sujeitos desde as suas inserções nesses mesmos contextos, nos quais constroem suas práticas. Nessa abordagem, enfatiza-se ora o nível microssocial das práticas que envolvem o fazer das pessoas, ora o nível macrossocial das influências contextuais sobre essas práticas. Isso remete à necessidade de uma delimitação entre os dois níveis, comumente realizada a priori pelo pesquisador (WILSON e JARZABKOWSKI, 2004). Nesse sentido, oferece-se uma proposta que permite reconhecer o espaço dos sujeitos sociais para definir essas delimitações. Para tanto, articulam-se no texto as seguintes contribuições teóricas: reflexões sobre a ideia de gestão como prática social (REED, 1989) e das representações sociais que oferecem uma alternativa para tratar os limites contextuais que envolvem o fazer das pessoas, dentro e fora das organizações (MOSCOVICI, 1961); as estratégias e táticas cotidianas dessas mesmas pessoas que evidenciam maneiras pelas quais os fazeres envolvem relações de interesses convergentes e divergentes (CERTEAU...

No size or density effect on alternative mate-locating tactics in the tropical damselfly Hetaerina rosea males (Odonata: Calopterygidae)

C. Peixoto,Paulo Enrique; De Marco Jr,Paulo
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 EN
Relevância na Pesquisa
37.15%
Males of the damselfly Hetaerina rosea may defend mating sites along river margins (resident males) or, alternatively, wander among different areas presumably searching for mates (nonterritorial males). Although the occurrence of territorial and nonterritorial males of H. rosea is very common in Brazil, studies examining which factors may be responsible for the adoption of alternative mate-locating tactics in this species are inexistent. We investigated the relationship between the adoption of these alternative mate-locating tactics by males of H. rosea and two possible causes: body weight and male abundance. We carried the study in three areas: sites 1, 2 and 3. Samples were monthly undertaken in sites 1 and 2 between September/2001 and August/2002 and in site 3 between May/1999 and January/2001. Using the scan method with fixed areas and mark-resighting techniques, we did not find any relationship between the proportion of nonterritorial males and male abundance per month on sites 2 (n=6) and 3 (n=7), indicating that the adoption of alternative mate-locating tactics is not affected by competition for territories. In the same way, nonterritorial and resident males showed similar body and thoracic weight measures (n=30 and n=27 for sites 2 and 3 respectively). Maybe the nonterritorial tactic is adopted by individuals searching for better territories or males that were evicted from their defended sites. The absence of relationship between weight and male territorial status is in accordance with other Hetaerina species. However...

Escape tactics and effects of perch height and habituation on flight initiation distance in two Jamaican anoles (Squamata: Polychrotidae)

Cooper, Jr,William E
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
Relevância na Pesquisa
36.98%
Escape by Anolis lizards is influenced by microhabitats and fight initiation distance increases with predation risk. Differences in microhabitat use among ecomorphs affect escape behavior, but only two studies have reported ecomorphological differences in flight initiation distance among Greater Antillean species. I studied effects of predation risk and microhabitats on escape behavior by conducting field experiments using two species of anoles, Anolis lineatopus and A. grahami, on the campus of the University of the West Indies at Mona, Jamaica. Because ecomorphological variation of anoles has evolved independently within each island of the Greater Antilles, but relationships between ecomorphs and escape behaviors are poorly known, I characterized microhabitat use and escape tactics, and determined relationships between flight initiation distance and two risk factors, habituation to human presence and perch height, in Anolis lineatopus, a trunk-ground anole and A. grahami, a trunk-crown anole. Sample sizes for A. lineatopus and A. grahami were 214 and 93, for microhabitat use and escape destinations, 74 and 34 for human presence and 125 and 34 for perch height. The two species occurred in similar microhabitats and exhibited similar escape tactics...