Abstract
Genome sequences can reveal the extent of inbreeding in small populations. Here, we present the first genomic characterization of type D killer whales, a distinctive eco/morphotype with a circumpolar, subantarctic distribution. Effective population size is the lowest estimated from any killer whale genome and indicates a severe population bottleneck. Consequently, type D genomes show among the highest level of inbreeding reported for any mammalian species (F ROH ≥ 0.65). Detected recombination cross-over events of different haplotypes are up to an order of magnitude rarer than in other killer whale genomes studied to date. Comparison of genomic data from a museum specimen of a type D killer whale that stranded in New Zealand in 1955, with 3 modern genomes from the Cape Horn area, reveals high covariance and identity-by-state of alleles, suggesting these genomic characteristics and demographic history are shared among geographically dispersed social groups within this morphotype. Limitations to the insights gained in this study stem from the nonindependence of the 3 closely related modern genomes, the recent coalescence time of most variation within the genomes, and the nonequilibrium population history which violates the assumptions of many model-based methods. Long-range linkage disequilibrium and extensive runs of homozygosity found in type D genomes provide the potential basis for both the distinctive morphology, and the coupling of genetic barriers to gene flow with other killer whale populations.
E mihi ana mātou ki a Tangaroa rāua ko Hinemoana, ko te kāinga o te kākahi/maki (ko ētahi o ngā kupu Māori mō te "killer whale", Orcinus orca). Waihoki, ka tika te mihi ki a Tūmatuenga, nā te mea, ki ōna wahi e pae ai ngā ika moana katoa. Ka mihi hoki mātou ki ngā whānau, ngā hapū, me ngā iwi e tiaki i tēnei taonga. Hoki atu ki te kākahi, nāna te moana hei rangatira me te aro o te rangahau nei. Mā te whakamātau i ngā raupapa ira o ngā tātai whakapapa o tēnei ika moana, e hura i te maha o ngā nohonga whakamoe kei roto i tēnei rāngai whāiti. Ko ngā whāinga rangahau e hora nei, ko te whakaraupapatanga tuatahi o ngā ira whakapapa o te momo kākahi ‘Type D’. Ko tōna āhuahanga he kiri kōheru, he mangu. Ko ngā moana matāo o Te Tiri o te Moana tōna kāinga. Mā te whakamātau i ngā raupapa ira nei, kāhore e huhua ana te maha o tēnei momo kākahi, hāunga e ērā atu momo. Koia e tohu ana i te iti o ngā uri o te rāngai ‘Type D’. E tohu ana ngā raupapatanga ira, he mea whakamoe tēnei rāngai kākahi ki a rātou anō (FROH ≥ 0.65). Ko ēnei ngā inenga whakamoe nui rawa puta i ngā uri katoa o ngā kararehe whāngote. Ko tēnei te tohu e tūpono ana ko tēnei iwi kākahi (type D) nei te tokoiti rawa o ngā momo kākahi kua rangahaua e te tangata, puta katoa i te ao. Kua tātari whakahāngai ngā raupapa ira o tētahi whakapapa kākahi (type D) o Paraparaumu (i mate whakauta i te tau 1955), ki ngā kāwai e toru o Cape Horne. Ahakoa he motuhake, he noho wehe ngā kāwai e rua nei, he hanga taurite te āhuaranga o ngā tātai heke, me nga tātai hono i waenga i ngā ira o ngā kāhui kākahi nei. He uaua rawa te kite i te motuhaketanga o te kāwai heke o ngā kākahi o Cape Horne nā te nui o ngā uri kua uhia ki te ao. He tohu pea tēnei i heke mai ēnei kāwai rerekē i tātahi puna puta-tahi. Engari rā, he nui noa atu nga āhuatanga hītori o enei kākahi e noho pohēhē ana, i runga i te uaua o ngā mahi hei whakapono i aua tatau. Koia pea tētahi āhuatanga i ngoikore ai ngā kōhanga tatau o te rangahau nei. Ahakoa kei te kākahi ‘Type D’ nei ōna ake āhuatanga, me tōna ake motuhaketanga, e kite hoki ana i ngā hononga-a-ira, ngā hononga kikokiko i waenganui i ngā kāwai whakapapa o ērā atu momo kākahi. He tohu tēnei i heke mai rātou i te tūpuna ōrite. Ahakoa tērā, kei te ngoto tonu ētahi tūahua hei ārai, hei aukati i te hono me te toha i waenga i ngā kāwai whakapapa nei.