Banca de QUALIFICAÇÃO: DIVNA DJOKIC

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : DIVNA DJOKIC
DATA : 29/10/2018
HORA: 15:00
LOCAL: Sala de Reuniões do Centro de Biociências
TÍTULO:

Assessing song exchange between South American Humpback Whale (Balaenoptera novaeangliae) stocks

PALAVRAS-CHAVES:

Humpback whales, acoustics, song comparison, song evolution, South America

PÁGINAS: 50
GRANDE ÁREA: Ciências Humanas
ÁREA: Psicologia
RESUMO:

South America hosts two breeding stocks of humpback whales. During the austral winter/spring, stock A occupies the south-west Brazilian waters of the Atlantic and stock G, the south-east of the Pacific. Both stocks feed in high latitudes during the austral summer: Stock A in South Georgia and Sandwich Islands, and stock G in Corcovado Gulf, Magellan Strait and South Shetland islands. The aim was to determine if these stocks interact vocally and if so what is dynamics of song exchange that results in the evolution of song structure. Various researchers contributed to the dataset which is comprised by songs recorded in the breeding range of each stock, on their migration path and in feeding areas. Songs from years 2016 and 2017 were processed, while songs from 2018 and 2019 will further be included. Songs were transcribed into a sequence of letters representing each unit. Three criteria were used to letter-code each unit: the spectrogram, the aural perception by the analyst and the position of the unit in the recording. A string of letters was then generated. The Levenshtein distance between two strings computes the minimum number of insertions, deletions and substitutions necessary to transform one string into the other. Levenshtein calculation was applied on these letter strings resulting in values of similarity for further construction of a distance matrix. The matrix shows each song’s structure. Further, bird literature was consulted in order to establish new methods for assessing humpback whale song in more detail. Measurements widely applicable in bird song research were adapted to correspond a study of a humpback whale song: element repertoire (in humpback whale literature known as unit dictionary, (2) versatility (disposition of all units and their ratio within the recording), (3) syntax consistency (placement of units), (4) total number of unit types, as the total number of units sung by each individual per song , (5) mean number of units per song and (6) plateau This new approach could help in identifying if song structure changes more on the breeding or on the feeding sites. Preliminary results suggest a high level of song evolution along the breeding season, especially for stock G. Lacking recordings from the Antarctica feeding region for 2016 and 2017 are preventing any inferences on song evolution during that period. Indirect conclusions can be driven from song comparison among breeding areas in consecutive seasons. It is noteworthy that this project lays on the biggest humpback whale bioacoustic research network formed so far in Latin America.

MEMBROS DA BANCA:
Externo à Instituição - ARTUR ANDRIOLO - UFJF
Externo ao Programa - 1753234 - GUSTAVO ZAMPIER DOS SANTOS LIMA
Presidente - 1863735 - RENATA SANTORO DE SOUSA LIMA MOBLEY