O uso de análises espaciais para o estudo de sistemas de acasalamento de baleias-jubarte (Megaptera novaeangliae): testando a teoria de hotspot
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Data
2019
Autores
Tomaselli, Rayane Gonçalves
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Universidade Estadual Paulista (Unesp)
Resumo
As baleias-jubarte (Megaptera novaeangliae) pertencem à família Balaenopteridae e realizam migrações sazonais. Uma das rotas de migrações é para Abrolhos (BA), conhecida como a principal área reprodutiva da espécie no Brasil. Sobre o comportamento reprodutivo vale destacar que o sistema de acasalamento é conhecido como lek flutuante, onde não há a centralidade dos indivíduos dentro da arena, pode haver competição pelo acesso a fêmea e os machos não oferecem cuidado parental. A comunicação das baleias-jubartes ocorre principalmente através dos sinais acústicos, tendo como principal característica as vocalizações dos machos que formam as canções e estas são mais complexas do que as das fêmeas. A canção possivelmente é utilizada para a atração de parceira, assim como para defesa e manutenção do território, também são muito comuns nas áreas de reprodução e pouco utilizadas nas áreas de alimentação, fortalecendo a hipótese de que a canção beneficia o sucesso do acasalamento. Desta forma, este trabalho teve por objetivo geral compreender os aspectos do comportamento reprodutivo dos machos cantores de baleia-jubarte através da utilização de sua localização espacial. Os dados acústicos e batimétricos foram coletados em trabalhos anteriores, assim como os pontos de localização e acompanhamento dos trajetos de alguns cantores. Para as análises deste trabalho utilizamos o software ArcGis com o método de Krigagem para realizar a interpolação da superfície batimétrica e em seguida classificamos e fizemos polígonos. A imagem foi exportada em formato raster e utilizada em ambiente R para auxiliar nas análises com o modelo Resource selection (RSF), através do estimador não paramétrico Kernel 95%. Os resultados encontrados reforçam a ideia de um lek flutuante, onde não há uma arena restrita e demarcada, pois 51% da área deste estudo foi ocupada por machos cantores, além de não haver forte seleção para a variável ambiental (batimetria), o que significa que a interação social da espécie parece se sobrepor a outros fatores, como fica mais explícito ao se olhar para os Kernels simultâneos, os quais também mostraram a pouca sobreposição das trajetórias, salientando que estão em áreas distintas e portanto devem apresentar mecanismos de espaçamento entre machos cantores.
Humpback Whales (Megaptera novaeangliae) belong to the Balaenopteridae family and perform seasonal migrations. One of the migration routes is to Abrolhos (BA), known as the main reproductive area of the species in Brazil. The mating system is believed to be a floating lek, because there is no centrality of individuals inside the arena, where there can be competition for access to the female and the male do not present parental care. The communication of Humpback Whales occurs mainly through acoustic signals, and male vocalizations are more complex than that of the female whales, forming songs. The song is possibly used for attraction of the partner, as for defense and maintenance of territory, they are also common in reproduction areas and little used in feeding areas, reinforcing the hypothesis that the song benefits mating success. Thus, this work aimed at comprehending the aspects of reproductive behavior of male singers through the use of their spatial location. The acoustic and bathymetry were collected in previous works as the location points and routes. For the analysis this work, we used the ArcGis software with the Krigagem method to achieve the interpolation of the bathymetric surface, it was then classified and made polygons. The image was exported in raster format and used in the R software to assist in the analysis with the Resource selection (RSF) model, using non-parametric Kernel 95% estimator. The results found reinforce the idea of a floating lek, where there is no restricted and demarcated arena, because 51% of the study area was occupied by male Humpback singers, in addition to not having strong selection for the environmental variable (bathymetry), which means that the behavioral ecology of the species seems to overlap with other factors, as it is more explicit when looking at the simultaneous Kernels, which also showed little overlap of the singers’ trajectories, emphasizing that they are in different areas and may have a spacing mechanism.
Humpback Whales (Megaptera novaeangliae) belong to the Balaenopteridae family and perform seasonal migrations. One of the migration routes is to Abrolhos (BA), known as the main reproductive area of the species in Brazil. The mating system is believed to be a floating lek, because there is no centrality of individuals inside the arena, where there can be competition for access to the female and the male do not present parental care. The communication of Humpback Whales occurs mainly through acoustic signals, and male vocalizations are more complex than that of the female whales, forming songs. The song is possibly used for attraction of the partner, as for defense and maintenance of territory, they are also common in reproduction areas and little used in feeding areas, reinforcing the hypothesis that the song benefits mating success. Thus, this work aimed at comprehending the aspects of reproductive behavior of male singers through the use of their spatial location. The acoustic and bathymetry were collected in previous works as the location points and routes. For the analysis this work, we used the ArcGis software with the Krigagem method to achieve the interpolation of the bathymetric surface, it was then classified and made polygons. The image was exported in raster format and used in the R software to assist in the analysis with the Resource selection (RSF) model, using non-parametric Kernel 95% estimator. The results found reinforce the idea of a floating lek, where there is no restricted and demarcated arena, because 51% of the study area was occupied by male Humpback singers, in addition to not having strong selection for the environmental variable (bathymetry), which means that the behavioral ecology of the species seems to overlap with other factors, as it is more explicit when looking at the simultaneous Kernels, which also showed little overlap of the singers’ trajectories, emphasizing that they are in different areas and may have a spacing mechanism.
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Palavras-chave
Sistema de acasalamento, Lek flutuante, Baleia-jubarte, Canção, Batimetria, Humpback whales, Song, Mating system, Floating lek, Bathymetry, Resource selection, Kernel 95%