Bridging the Gap: The Holocene

The Holocene is an interesting time period to investigate as it is more like our present climate than during the Pleistocene where mass extinctions and migrations occurred between glacials and interglacials. During the Holocene, we experienced periods of cooling (little ice age) and periods of warming (medieval warming period). The warming periods can be useful in understanding as they are the closest to the climate change we are currently experiencing. Bruyn et al wrote a paper this year called ‘Faunal histories from Holocene ancient DNA’ which looks at the changes in species, distribution and migration during the Holocene. DNA can be used to calculate the genetic diversity of a species at any given time. A large diversity of a particular species suggests a larger population, perhaps allowed by migration and expansion without rear contraction. An example of this is the Elephant seal which colonised new southern areas during the Holocene and increased its population and genetic diversity.

However, the Holocene also gave rise to many species extinctions due to its variability in climate. During the late Holocene period this was most apparent as habitats were degraded due to climate variability, including the southern elephant seals’ newly found habitats. (Talking of elephant seals, did anyone see that graphic fight between them on Frozen Planet last week?!)

Although climate triggered migrations were apparent during the Holocene and Late Glacial Maximum, these migrations were often on a smaller and/or slower scale than any migratory movements seen within the last century due to climate change.

References:

1. Bruyn et al 2011, ‘Faunal histories from Holocene ancient DNA’, Trends in ecology and evolution, 26, 8, 405 – 413.