Galapagos and Californian sea lions are separate species


This is ‘Freediving with sea lions, dolphins, sharks, and others in the Galapagos. Video by Felix Leander’.

From Frontiers in Zoology:

Accurate formal taxonomic designations are thought to be of critical importance for the conservation of endangered taxa. The Galapagos sea lion (GSL), being appreciated as a key element of the Galapagos marine ecosystem, has lately been listed as ‘vulnerable’ by the IUCN. To date there is, however, hardly any scientific evidence, whether it constitutes a separate entity from its abundant Californian neighbour (CSL). In this paper, we delineate the taxonomic relationships within the genus Zalophus being comprised of the Galapagos sea lion, the Californian sea lion and the already extinct Japanese sea lion (JSL). …

Conclusions

Based on molecular evidence we build a case for classifying the Galapagos sea lion (Zalophus wollebaeki), the Californian sea lion (Zalophus californianus) and the Japanese sea lion (Zalophus japonicus) as true species. As morphological characters do not necessarily fully reflect the rapid divergence on the molecular level, the study can be considered as a test case for deriving species status from molecular evidence. We further use the results to discuss the role of genetics in conservation policy for an organism that already is under the general protection of the habitat it lives in.

Galapagos kelp: here.

After several weeks of unusually high levels of sea lion strandings and high numbers of dead sea lions washing up on the beaches of Southern California, the local authorities have declared ‘An unusual mortality event’ (UME): here.

California sea lions have fully rebounded under the protection of the Marine Mammal Protection Act, with their population on the West Coast reaching carrying capacity in 2008 before unusually warm ocean conditions reduced their numbers, according to the first comprehensive population assessment of the species: here.

Islands in the sea: extreme female natal site fidelity in the Australian sea lion, Neophoca cinerea: here.

12 thoughts on “Galapagos and Californian sea lions are separate species

  1. Sea lion cubs found dead in Galapagos Islands

    By IANS
    Thursday November 22, 02:17 PM

    Quito (Ecuador), Nov 22 (IANS) Rangers of the Galapagos national park have discovered seven dead cubs of the highly threatened sea lion on the San Cristobal Island, Spanish news agency EFE reported Thursday.

    The carcasses bore cut marks and windpipes had been ruptured, according to a report, which blamed the deaths on roaming dogs.

    Park management, police environmental crime unit and other agencies have launched an operation to capture the three dogs suspected of the killings.

    Earlier in July, carcasses of eight endangered tortoises were discovered on the Island, which were killed by poachers. The three adult females were over 80 years old.

    On June 26, Unesco declared the Galapagos Islands a World Heritage Site in danger, citing widespread environmental degradation.

    The Ecuadorian government, which had already sounded an alert on the threats to the Galapagos, said, the islands’ inclusion on the Unesco list provided an opportunity for the international community to help Ecuador protect highly endangered species of the marine animals.

    The law here prohibits hunting, capture and trade of endangered flora and fauna.

    The Galapagos Islands are in the Pacific Ocean, about 1,000 km west of Ecuador. They served as a natural laboratory that inspired English scientist Charles Darwin to develop his theory of evolution, natural selection and the origin of species.

    http://in.news.yahoo.com/071122/43/6nk8l.html

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  2. California’s ancient kelp forest

    The kelp forests off southern California are considered to be some of the most diverse and productive ecosystems on the planet, yet a new study indicates that today’s kelp beds are less extensive and lush than those in the recent past.

    The kelp forest tripled in size from the peak of glaciation 20,000 years ago to about 7,500 years ago, then shrank by up to 70 percent to present day levels, according to the study by Rick Grosberg, professor in the Department of Evolution and Ecology and the Center for Population Biology at UC Davis, with Michael Graham of the Moss Landing Marine Laboratory and Brian Kinlan at UC Santa Barbara.

    Kelp forests around offshore islands peaked around 13,500 years ago as rising sea levels created new habitat and then declined to present day levels. The kelp along the mainland coast peaked around 5,000 years later.

    This transition from an extensive island-based kelp system to a mainland-dominated system coincided with conspicuous events in the archaeological record of the maritime people in the region, suggesting that climate-driven shifts in kelp ecosystems impacted human populations that used those resources.

    Understanding the past history of a population is crucial to understanding its genetics in the present, Grosberg said.

    “Kelp is interesting because it disperses only over short distances,” Grosberg said. “Populations can become genetically isolated from one another even if they are quite close together.”

    “We wanted to know how connected the coastal kelp populations were since the last glacial maximum,” he said.

    On land, scientists can reconstruct the history of a forest or grassland from fossilized pollen or leaves. But kelp do not make pollen, and marine sediments do not preserve a good record of the plants.

    The researchers used depth charts of the southern California coastline and information from sediment cores on past nutrient availability to reconstruct potential kelp habitat as sea levels changed over the last 20,000 years.

    “We could reconstruct changes in kelp cover at a scale of 500 years and determine how fragmented or connected the populations were,” Grosberg said.

    People have lived off the produce of kelp forests when resources on land dwindled, and those changes are recorded in shell middens and other traces. That archaeological record can now be compared with the ecological history to get a more complete picture of California’s coast.

    “Now we know what was happening with kelp, what was happening with the ecology on land, and what the people were doing,” Grosberg said.

    ###

    The study was published online Oct. 21 in the journal Proceedings of the Royal Society B.

    http://www.eurekalert.org/pub_releases/2009-11/uoc–cak111009.php

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