Evaluation of tree frog tracking methods using Phyllomedusa trinitatis (Anura: Phyllomedusidae)

Evaluation of tree frog tracking methods using Phyllomedusa trinitatis (Anura: Phyllomedusidae). Investigating the behaviors of small, inconspicuous and cryptic animals can be helped by tracking their movements. The effectiveness of different tracking methods can be very dependent on behavior and ecology; radio-telemetry and thread bobbins have been widely used over a range of environments and taxa, but each presents problems. Phyllomedusa trinitatis is a tree frog found in Trinidad and Venezuela and has mostly been studied for its nest building and breeding behavior, but little is known about its behavior away from breeding ponds. This study aimed to identify the strengths and weaknesses, including impacts on the welfare of these frogs, of different tracking methods, thread bobbins and radio-telemetry, when used to track them in a dense rainforest environment. A pilot study found that fuorescent dyes were unsuitable for this species. Individuals were tested in laboratory conditions to determine the application time for each tracker and to test on this species the tracker 10% weight rule. The rule was found to be too restrictive for this frog; trackers up to 15% of body weight were used with no signifcant impacts on distances travelled. Frogs became lethargic when bearing trackers longer than two days, so we limited tracking in the feld to one overnight period. Of the 26 frogs tracked in the feld (nine radio-tags, 17 bobbins), 16 were successful (six radio-tags, 10 bobbins) and six untracked frogs were found in the feld during the day as controls. Bobbins were cheaper and allowed visualization of the detailed path taken, including substrates used, but caused more bruising due to entanglement, and individuals tracked with this method were less likely to return on following nights to the breeding ponds. Radio-tags had no threat of entanglement but were much more expensive and the signal was interrupted by the dense vegetation preventing some individuals from being found. There were no signifcant differences in the distances travelled by tracked or control frogs, from which we infer that these tracking methods did not impact signifcantly on movement. It appears that neither of these tracking methods work perfectly for Phyllomedusa in a densely vegetated environment, and that both incur welfare problems. Our study emphasizes the need to test out tracking methods on each species in each habitat.Avaliação de métodos de rastreamento de pererecas usando Phyllomedusa trinitatis (Anura: Phyllomedusidae). A investigação do comportamento de animais pequenos, inconspícuos e crípticos pode ser auxiliada pelo rastreamento de seus movimentos. A efciência de diferentes métodos de rastreamento pode ser muito dependente de seu comportamento e ecologia; rádiotelemetria e bobinas de rastreamento têm sido largamente utilizadas com uma variedade de ambientes e táxons, mas cada uma dessas técnicas apresenta problemas. Phyllomedusa trinitatis é uma perereca encontrada em Trinidad e na Venezuela e tem sido estudada principalmente no que se refere a seu comportamento reprodutivo e de construção de ninhos, mas pouco se sabe sobre seu comportamento longe das lagoas reprodutivas. Este estudo teve como objetivo identifcar vantagens e desvantagens de diferentes métodos de rastreamento (bobinas de rastreamento e rádio-telemetria), incluindo impactos no bem-estar desses anuros, quando usados para rastreá-los em um ambiente de foresta pluvial densa. Um estudo-piloto mostrou de tintas fuorescentes foram inadequadas para essa espécie. Indivíduos werforam testados em condições laboratoriais para determinar o tempo de aplicação de cada rastreador e para testar nessa espécie a regra dos 10% do peso. A regra mostrou-se muito restritiva para essa perereca; rastreadores com até 15% do peso corpóreo foram usados sem impactos signifcativos sobre a distância percorrida. Os animais tornaram-se letárgicos quando portavam rastreadores por mais de dois dias, de forma que limitamos o rastreamento no campo a um período de uma noite. Dos 26 indivíduos rastreados no campo (nove com radiotransmissores, 17 com bobinas), 16 foram bem-sucedidos (seis com radiotransmissores, 10 com bobinas) e seis indivíduos não-rastreados foram encontrados no campo durante o dia como controles. As bobinas são mais baratas e permitem a visualização detalhada do caminho percorrido, incluindo os substratos utilizados, mas causam mais injúrias devido ao entrelaçamento, e os indivíduos rastreados com este método eram menos propensos a retornar nas noites seguintes para as lagoas de reprodução. Os radiotransmissores não ofereciam a ameaça de emaranhamento, mas são muito mais caros, e o sinal era interrompido pela densa vegetação, impedindo que alguns indivíduos fossem encontrados. Não houve diferenças signifcativas nas distâncias percorridas por indivíduos rastreados e animaiscontrole, do que inferimos que esses métodos de rastreamento não tiveram impacto signifcativo sobre o movimento. Parece que nenhum desses métodos de rastreamento funciona perfeitamente para Phyllomedusa em um ambiente com vegetação densa e que ambos geram problemas de bem-estar. Nosso estudo enfatiza a necessidade de testar métodos de rastreamento para cada espécie em cada habitat

Breeding site attendance and breeding success in Phyllomedusa trinitatis (Anura: Phyllomedusidae)

Using a natural marker, we documented breeding site attendance patterns by males and females of the Trinidad Leaf Frog, Phyllomedusa trinitatis. We followed attendance at a cluster of three isolated ponds over 53 and 56 consecutive nights in 2016 and 2019 respectively. Most females attended only once, but for those that attended more than once we calculated an inter-nesting interval (mean 27.6 days, N = 7). Males showed high pond fidelity, but some did attend at two of the ponds, always with a strong preference for one of them. Males showed three attendance patterns. A few attended on multiple consecutive nights (maximum, 19 nights); more were sporadic (one attended seven times over 46 nights with gaps of 15 and 19 days in the sequence); some attended only once (2016: 12, 2019: 15), but most were found to be present on multiple nights (2016: 38, 2019: 32). Our analysis suggested that these latter frogs were either newly recruited individuals or had been predated during the study. Our data show that rainfall has some influence on attendance. We found no relationship between male body condition and attendance pattern. In addition, there was no evidence that a particular male attendance pattern was optimal for breeding success

Environmental correlates of sexual signaling in the Heteroptera : a prospective study

EG is supported by a School of Biology, University of St Andrews PhD Studentship.Sexual selection is a major evolutionary process, shaping organisms in terms of success in competition for access to mates and their gametes. The study of sexual selection has provided a rich empirical and theoretical literature addressing the ecological and evolutionary causes and consequences of competition of gametes. However, there remains a bias towards individual, species-specific studies, whilst broader, cross-species comparisons looking for wider-ranging patterns in sexual selection remain uncommon. For instance, we are still some ways from understanding why particular kinds of traits tend to evolve under sexual selection, and under what circumstances. Here we consider sexual selection in the Heteroptera, a sub-order of the Hemiptera, or true bugs. The latter is the largest of the hemimetabolous insect orders, whilst the Heteroptera itself comprises some 40,000-plus described species. We focus on four key sexual signaling modes found in the Heteroptera: chemical signals, acoustic signaling via stridulation, vibrational (substrate) signaling, and finally tactile signaling (antennation). We compare how these modes vary across broad habitat types and provide a review of each type of signal. We ask how we might move towards a more predictive theory of sexual selection, that links mechanisms and targets of sexual selection to various ecologies.Publisher PDFPeer reviewe

Environmental correlates of sexual signaling in the Heteroptera:a prospective study

Sexual selection is a major evolutionary process, shaping organisms in terms of success in competition for access to mates and their gametes. The study of sexual selection has provided a rich empirical and theoretical literature addressing the ecological and evolutionary causes and consequences of competition of gametes. However, there remains a bias towards individual, species-specific studies, whilst broader, cross-species comparisons looking for wider-ranging patterns in sexual selection remain uncommon. For instance, we are still some ways from understanding why particular kinds of traits tend to evolve under sexual selection, and under what circumstances. Here we consider sexual selection in the Heteroptera, a sub-order of the Hemiptera, or true bugs. The latter is the largest of the hemimetabolous insect orders, whilst the Heteroptera itself comprises some 40,000-plus described species. We focus on four key sexual signaling modes found in the Heteroptera: chemical signals, acoustic signaling via stridulation, vibrational (substrate) signaling, and finally tactile signaling (antennation). We compare how these modes vary across broad habitat types and provide a review of each type of signal. We ask how we might move towards a more predictive theory of sexual selection, that links mechanisms and targets of sexual selection to various ecologies