[{"id":158,"title":"What’s black and white and eating stuff all over? Hypotheses for the evolution of killer whale coloration and similar coloration patterns in prey species","sha":"70f5d0970e8f60a595f62f31a34701a0","user_id":562,"state":"published","body":"The greatest diversity of killer whale forms–or possible (sub)species – is in the Antarctic. One reason may be because killer whales originated in, or near, the Antarctic, which would also explain their large size - an example of Bergmann’s rule [http://en.wikipedia.org/wiki/Bergmann%27s_rule], i.e. species that evolve in higher latitudes are larger. \r\nIf killer whales did evolve in the Southern Ocean, penguins would have been an abundant prey source. There was a great diversity of penguin species when toothed whales arose [http://rsbl.royalsocietypublishing.org/content/9/6/20130748]. The distinctive black and white coloration of killer whales could have been aggressive mimicry [http://en.wikipedia.org/wiki/Aggressive_mimicry], allowing them to approach penguins - Gerlache killer whales (small type B) appear feed preferentially on penguins today [https://swfsc.noaa.gov/uploadedFiles/2010_Pitman%20and%20Durban_Polar%20Biology_Penguin%20predation.pdf]. Killer whales may then have diversified to fill other niches and eat other prey beyond the Southern Ocean. Many species of porpoises/ delphinids upon which killer whales prey also share their predators’ black and white coloration. This may again be mimicry, but defensive mimicry [http://en.wikipedia.org/wiki/Mimicry] – prey species resembling their chief predator gain a few precious seconds of confusion when they approach. These hypotheses might explain the ubiquitous and convergent black and white coloration in the cetacean prey of killer whales, and their unusual black and white color pattern.\r\n","created_at":"2015-04-30T17:49:49.056Z","updated_at":"2024-07-18T08:53:15.089Z","zenodo_id":28316,"doi":"http://dx.doi.org/10.5281/zenodo.17281","subject":null,"tags":["killer whale","orcinus orca","mimicry","penguins","evolution"],"vote_count":3,"view_count":1,"score":3.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null},{"id":157,"title":"Are male killer whale (Orcinus orca) dorsal fins indicators of fitness?","sha":"42d8749002898fcf9e86b010fe397c88","user_id":562,"state":"published","body":"The females of many animals may assess the fitness and health of males via displays or physical features, such as the tail of a peacock [http://en.wikipedia.org/wiki/Signalling_theory]. Physical features may be a “handicap” that fit males can overcome. Male killer whales have large (2m), straight dorsal fins that project perpendicularly from their backs whereas females and juveniles have smaller, curved hydrodynamic fins. The large, straight-edged fin of the male would produce substantive drag and would presumably be a handicap. Are the large dimorphic fins of male killer whales a secondary sexual characteristic, via which females can visually assess male fitness? Dorsal fins are comprised of connective tissue, and bent or collapsed male killer whales fins are rare in the wild. The percentage of male killer whales with collapsed fins ranges from 1%-5% in British Columbia [http://www.amazon.com/Killer-Whales-Genealogy-Columbia-Washington/dp/0774804696/ref=sr_1_fkmr0_1?ie=UTF8\u0026qid=1430411496\u0026sr=8-1-fkmr0\u0026keywords=ford+%26+killer+whales+%26+1994]. Injury or poor health has been associated with collapsed fins [http://www.nmfs.noaa.gov/pr/interactions/injury/pdfs/day2_1155_baird_gorgone.pdf]: 2 of 3 animals reported in Alaska with collapsed fins had been exposed to the Exxon Valdez oil spill [http://www.amazon.com/Killer-Whales-Southern-Alaska-Matkin/dp/0963346792/ref=sr_1_fkmr0_1?ie=UTF8\u0026qid=1430411410\u0026sr=8-1-fkmr0\u0026keywords=Matkin%2C+C.O.%2C+Ellis%2C+G.M.%2C+Saulitis%2C+E.L.%2C+Barrett-Lennard%2C+L.G.%2C+Matkin%2C+D.R.+1999.+Killer+whales+of+southern+Alaska.+North+Gulf+Oceanic+Society%2C+Homer%2C+Alaska.+96+pp.]; in New Zealand, 23% of males in one population had misshapen dorsal fins, but only one of these, who had suffered an injury as the result of entanglement, had a completely collapsed fin [http://www.aquaticmammalsjournal.org/share/AquaticMammalsIssueArchives/1998/AquaticMammals_24-02/24-02_Visser.pdf]. ","created_at":"2015-04-30T17:02:00.982Z","updated_at":"2015-06-20T09:23:23.129Z","zenodo_id":28314,"doi":"http://dx.doi.org/10.5281/zenodo.17280","subject":null,"tags":["killer whale","orcinus orca","dorsal fin","honest signalling","handicap principle","sexual selection"],"vote_count":4,"view_count":1,"score":4.1,"deleted":false,"muted":false,"tweeted":true,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null}]