A Small mammal of the Quaternary: A Review of Brace et al
During
the late-Quaternary it has been commonly noted that many large
animals (the megafauna) became
extinct. The smaller animals are often ignored, but this is probably because many of them survived into the present day (Brace
et al., 2012).
One such species is the collared lemming, which still exists in arctic regions today. This is a cold-adapted animal, which thrives during glacial conditions. Though this species
remains extant, and it is often assumed that small animals were not
largely affected by late-Quaternary extinctions, this lemming
possesses a more complex story.
The Story
Data collected from three sites suggests that the collared lemming underwent a series of localised extinction events, followed by recolonisation of those areas after initial disappearance. Several of these extinctions occur during climatically warm episodes (Brace et al., 2012). As a cold adapted species, it makes sense that regional extirpation would occur at this time. Whilst in contrast one of these events occurs during a period of cooler temperatures (Last Glacial Maximum). This coincides with the only known reduction in Mammuthus primigenius presence across the North of Europe during this time frame (Brace et al., 2012). So, it seems that this period of climate change has had a significant enough affect as to limit the distributions of both some of the large and small animals of the late-Quaternary.
Why so many extinctions?
-
It may have been climate, but the lemming was still occurring at Pot Cave, which was further North (see map).
-
A link between climate and ecology: with a change in temperature and rainfall, there will be a corresponding change in vegetation type. This could have caused the repeated regional demise of the collared lemming. During warmer conditions vegetation was replaced by southern communities (Prost et al., 2010). Lemmings did not survive well in these environments, and experienced significant population contractions during these intervals (Brace et al., 2012). This could explain the repeated extinction events.
- It could be a response to loss in genetic diversity. Without this diversity, a population can fail to reproduce (Brace et al., 2012). Lack of genetic variation can ultimately contribute to population collapse (Lacy, 1997), which is a possible explanation.
Lemmings have so far survived the Quaternary, and continue to live in northern regions today. Contrary to popular belief, they do not walk off cliffs (just for the record).
If
the article by Brace et al (2012) is too
dense, I suggest taking a look at this summary article in the Daily Mail:
Thanks for Reading!
Resilient little devils aren't they!!
ReplyDeleteYes they became repeatedly extinct in certain areas through time, before recolonizing them again in more favorable conditions. Today they are only really present in Arctic regions.
DeleteI think personally that this is very interesting. It is good to know that they recolonise, rapidity if it is possible to determine this might also be of interest.
ReplyDelete