Microevolution of a red squirrel population caused by climate change

Vincent ArcegaApril 23, 2013

PhylogenyKingdom:AnimaliaPhylum:ChordataClass:MammaliaOrder:RodentiaFamily:SciuridaeGenus:TamiasciurusSpecies:T. hudsonicus

FactsLength30 cmWeight 280 gLifespan 6 yearsHabitat trees

DietConifer seeds, flowers, berries.

Predation Birds, lynx, coyotes.

www.en.wikipedia.org

Genetic and plastic responses of a northern mammal to climate change

Authors:Denis Reale, Andrew G. McAdam,

Stan Boutin and Dominique Bertaeaux

Genetic and plastic responses of a northern mammal to climate change

As climate increases due to global warming animals must cope through physiological changes or microevolution.

Purpose of studyMicroevolution is the changes

in allele frequencies that occur over time within a population. This change is due to four different processes: mutation, selection (natural and artificial), gene flow, and genetic drift.

Purpose of studyRed squirrels are studied for how

they have adapted to the climate change with changes in spring weather and food abundance.

Purpose of StudyBreeding was documented over

four generations.Parturition date is hereditary. If

parturition date changes then the results may be from microevolution.

Life span of Red Squirrel?

ReproductionRed squirrels breed once or twice

a year, depending on their geographic location

The breeding season begins in midwinter from March to May. Followed by August to early September.

Reproduction* Females are in estrus only 1

day per breeding season!Conception usually occurs within

a few hours of mating.

Climate ChangeEarth's average temperature has

risen by 1.4°F over the past century, and is projected to rise another 2 to 11.5°F over the next hundred years

(www.epa.gov)

www. epa.gov

The orange line shows the first arrival of frost in the fall, which is occurring later in the year than previously. The green line shows the timing of the last spring frost, which is occurring earlier in the year than previously.

Material and MethodsThe study was near Kluane Lake,

Yukon, Canada. The habitat was open boreal forest

325 squirrels were ear-taggedReproductive activity monitored

yearly.

Breeding ValueThis represents the combined

additive effects of all an individual’s genes for a given trait and changes in estimated breeding values (EBVs).

Breeding ValueThis approach helps differentiate

between temporal phenotypic changes due to genetic and environmental sources

Environmental changes and reproductionFemales born in 1989 and 1998

lifetime parturition date was calculated.

Food is counted every August.Yearly spruce cones were a

measure of the average food abundance.

Maternal EffectsFive maternal characteristics that

may affect EBV:Maternal AgeLitter SizePostpartum body massMaternal reproductive

investmentSpruce cone index.

Microevolutionary changes in parturition dateFemales born in 1989 and 1991

were assigned generation oneFemales after 1991 regardless of

the year born were 1 generation higher than their mother.

Results Factor: EnvironmentSpring temperature has increased by nearly

2˚ CNo particular trend for precipitationNumber of cones have increased by over 35%

Note: For weather temperatures you can make a rough conversion from Celsius to Fahrenheit by doubling the figure and adding 30.

Results Factor: ReproductionThe past decade has shown

advance increase in parturition date.

Red squirrels born in 1989: from January 1 to May 8 (128 days).

Results Factor: ReproductionRed squirrels born in 1998: from

January 1 to April 20 (110 days)

128 days – 110 days = 18 daysReproduction has changed 18

days in the past decade.

Phenotypic PlasticityFood abundance had large effect

on reproduction.This indicates a large amount of

phenotypic plasticity and a strong effect on breeding.

Figure 1

Figure 2 Figure 3

In ConclusionIn the past 27 years Yukon has

increased in spring temperatures and also an increase in food.

The response was an 18 day advancement in breeding.

The red squirrels have experienced phenotypic changes and microevoltuion.

In ConclusionFrom the author:

“The combination of phenotypic changes within generations and microevolutionary changes among generations resulted in large phenotypic responses to rapid changes in environmental conditions experienced by this population of squirrels over the past 10 years.”

Questions, Comments, Concerns.