Whistle repertoire and structure reflect ecotype distinction of pantropical spotted dolphins in the Eastern Tropical Pacific - Scientific Reports
www.nature.com
The pantropical spotted dolphin in the Eastern Tropical Pacific (ETP) is found in two genetically and phenotypically diverged ecotypes, coastal and offshore. These habitats have distinct acoustic characteristics, which can lead to the evolution of distinct acoustic communication. Whistles are sounds widely used by dolphins to mediate species and individual recognition and social interactions. Here, we study the whistle acoustic structure and repertoire diversity of offshore and coastal pantropical spotted dolphins. Our results show that there is significantly more within- and across-group variation in whistle fundamental frequency between ecotypes than between offshore groups and between coastal groups. A Random Forest classification analysis performed with an accuracy of 83.99% and identified duration, peak and minimum frequency as the most informative variables for distinguishing between ecotypes. Overall, coastal spotted dolphins produced significantly shorter whistles that were significantly lower in frequency (peak, minimum and maximum, and start and end) than offshore dolphins. Ecotypes produced whistle repertoires that were similar in diversity, but different in contour composition, with the coastal ecotype producing more upsweep whistles than offshore dolphins. The results of this study suggest that acoustic adaptations to coastal and offshore environments could be important contributors to intraspecific variation of dolphin whistle repertoires.
  • @HaggunenonsOPM
    1•1 year ago

    Summary made by GPT-4/Quivr

    This document is a scientific study on the whistle repertoire of a species of dolphins, specifically the pantropical spotted dolphins. The researchers used various methods to analyze the whistle sounds made by these dolphins, including Mean Decrease in Accuracy (MDA) and Mean Decrease in Gini (MDG) to assess the importance of different variables in the whistle sounds. They also used a confusion matrix and Cohen’s Kappa statistic to evaluate the performance of their model.

    The researchers used a program called ARTwarp to categorize the whistle contours, or shapes, based on their similarity. They set a vigilance parameter to 96%, which means that the program would categorize a new whistle contour as similar to a reference contour if it was 96% similar. This vigilance level was chosen based on previous research on bottlenose dolphin whistles.

    The study was conducted in various locations, including coastal and offshore waters of the Eastern Tropical Pacific (ETP), Northern Nicaragua, Southern Nicaragua, and El Salvador. The researchers used different types of hydrophones to record the dolphin whistles, and they used a program called RAVEN PRO to create spectrograms of each recording.

    The researchers found that the whistle repertoire of the pantropical spotted dolphins is diverse and complex. They suggest that this acoustic plasticity, or the ability to produce a wide range of sounds, may be crucial for these dolphins to adapt to increasingly noisier habitats due to climate change. They also suggest that their combined analysis of whistle acoustic structure and repertoire features could be used in the development of dolphin species and population classifiers for passive acoustic monitoring programs.

    In simpler terms, this study is about understanding the different types of sounds that a specific type of dolphin makes. The researchers found that these dolphins can make a wide variety of sounds, which might help them adapt to changes in their environment. This research could also help us better monitor and understand dolphin populations in the future.