Previsão de ocupação de anuros usando sensoriamento de variáveis ambientais e modelos Autocodificadores

Neste trabalho apresentamos um modelo de previsão da distribuição geográfica de anuros baseado em uma Rede Neural Autocodificadora. O problema de previsão é tratado como uma tarefa de classificação One-Class, em que a localização conhecida dos indivı́duos é representada através de suas coordenadas espaciais, temporais e variáveis meteorológicas correlacionadas. O modelo mostrou alto grau de acuidade quando utilizado para prever a ocorrência de sapos da espécie Bufo Americanus no sul do Canadá. O método proposto é computacionalmente leve e pode ser acoplado a redes de sensores para monitoramento ambiental.

Is there a role for stripes of adults and colour of larvae in determining the avoidance of the Colorado potato beetle by the American toad?

It has been suggested that the stripes on the elytra of the adult Colorado potato beetle ( Leptinotarsa decemlineata (Say, 1824); Coleoptera: Chrysomelidae) and the red colouration of the larvae are aposematic characters warning predators of their distastefulness as prey. The role of stripes and red colour in determining the avoidance behaviour of the American Toad ( Bufo americanus Holbrook, 1836 = Anaxyrus americanus (Holbrook, 1836); Anura: Bufonidae) for the Colorado potato beetle was investigated in a series of laboratory tests. The behaviour of toads exposed to wild Colorado potato beetles was compared with that of toads exposed to genetic mutant Colorado potato beetles without elytral stripes. Tests confirmed the distastefulness of adult and larval stages and demonstrated the development of prey avoidance (cessation of feeding in spite of hunger) combined or not to behavioural displays where the toad plants down, crouches, and turns away or shows wincing, prey dropping, and mouth gaping after snapping at the beetle. However, toads showed the same response to mutant adult beetles without stripes and to mutant larval beetles without the red colour as to wild adult beetles with stripes and to wild red larvae. Results indicate that the stripes and the red colouration of the Colorado potato beetle do not constitute aposematic characters for the toad.

Gyrinicola chabadamsoni n. sp. and G. tba (Dinnik 1933) (Nematoda, Oxyuroidea) from tadpoles of the hybridogenetic complex Rana lessonae-esculenta (Amphibia, Ranoidea)

Two morphological types of the viviparous oxyurid nematode Gyrinicola were recovered from waterfrog tadpoles in France (Ain department, Rhône-Alpes region) and assigned to two species: G. tba (Dinnik 1930), redescribed, and G. chabadamsoni n. sp. Gyrinicola tba is close to G. batrachiensis (Walton 1929) and G. chabaudi Araujo and Artigas 1982 in that the female possesses a long tail and few cuticular buccal flaps. The new species, type host Rana kl. esculenta, is distinct by several characters: in females, by the 12 cuticular buccal flaps with internal crests, short caudal filament, short ovary producing embryonated eggs and large uterine pouch containing males and embryos, like in G. japonica Yamaguti 1938, and narrower thick-shelled eggs with subapical elongated operculum; in males, by the round genital cone, the third caudal pair of papillae at mid tail, length of the body and caudal part. Gyrinicola tba and the new species were found in R. lessonae and in the hybrid R. kl. esculenta but each with different seasonal infection rates. Comparative analyses of the data from the five Gyrinicola species were done. All females have one genital tract producing thick-shelled female eggs. The second genital tract is one of four types corresponding to different reproductive patterns: i) it forms a uterine pouch containing males in G. chabadamsoni and G. japonica; ii) it forms a slender uterus containing numerous autoinfective larval stages in G. batrachiensis from R. clamitans; iii) it forms a slender uterus containing only a few embryos in G. tba and G. chabaudi; and iv) it has regressed in G. batrachiensis from Bufo americanus. Haplodiploidy is expected or proved for types i) and ii) and thelytoky for types iii) and iv).

Variation in amount of surrounding forest habitat influences the initial orientation of juvenile amphibians emigrating from breeding ponds

Juvenile dispersal is important for the persistence of ​amphibian populations. Previous studies have observed nonrandom orientation in juvenile amphibians emigrating from breeding ponds; however, the environmental cues associated with these movements are not well understood. We examined the emigration behavior of recently metamorphosed juveniles of three pond-breeding amphibian species from three woodland ponds. We found that juvenile small-mouthed salamanders ( Ambystoma texanum (Matthes, 1855)), American toads ( Bufo americanus Holbrook, 1836), and wood frogs ( Rana sylvatica LeConte, 1825) exhibited nonrandom orientation upon exiting the breeding ponds. Furthermore, we found a positive relationship between captures of juvenile small-mouthed salamanders and wood frogs and width of the surrounding forest habitat, indicating that these species are selecting areas with broader forested habitat upon exiting the breeding ponds. Our results indicate that migrating juvenile amphibians may rely on direct environmental cues because the orientation of small-mouthed salamanders and wood frogs was influenced by width of the surrounding forested habitat. These observations support previous studies suggesting that maintaining forest habitat, along at least a portion of breeding ponds, is important for the persistence of amphibian populations.

Does physical or acoustical disturbance cause male pickerel frogs, Rana palustris, to vocalize underwater?

Male pickerel frogs (Rana palustris) vocalize both above water and underwater. Males have a complex vocal repertoire consisting of an advertisement call and two additional call types (i.e., aggressive calls) that can be elicited by the playback of a conspecific advertisement call. Additionally, in a previous study, males in these playbacks often dove and vocalized underwater for a few minutes before returning to the surface. The purpose of this study was to investigate whether physical or acoustical disturbance cause male pickerel frogs to call underwater. Experimental manipulations were performed with resident males that, initially, were calling above water. In the first, 16 males were physically disturbed with the intent to make them dive underwater. Eleven of these began to call underwater within 10 to 95 seconds and continued for up to four minutes before returning to calling above water. The second experiment involved playbacks in which males were disturbed acoustically by two minutes of continuous advertisement calling from either one Bufo americanus or Pseudacris crucifer male. Only one of 15 males dove and then called underwater in response to B. americanus calls even though most subjects emitted aggressive calls during the test period, and no male called underwater in response to P. crucifer calls (n = 13). In conclusion, male pickerel frogs will shift to underwater calling in response to a physical disturbance, but do not shift in response to the sounds of one heterospecific caller.