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rapid microevo in migratory beh. in a wild bird species - Coggle Diagram
rapid microevo in migratory beh. in a wild bird species
blackcaps breeding in Europe since 1950 have been found increasinly to winter in brtian opposed to their classic migratory route southwest like most of their conspecifics
to determine if this new route was gentically based they caught 20 wintering black caps and captively bred 41 offspring in southwest germany. Than as a control group 49 southwest german nestling were transfered to the rearing site.
birds were testing on their oritentation 15-20 times using a modified Emlen techique
British wintering adult's and there off spring had a statistically significant orientation just north of west with respect to mean direction and dispersion of individual vectors differing from the german control which oritened classicaly southwest
wintering british offspring had a more westerly offspring independtly for their parents compared to the german juviniles & most variation of orentation was between rather than within sibling groups
9 signifcant diffrences of mean direction b/w non-siblings but none between siblings, indicates a genetic compontet to the variance of orentation
therefore they differ in innate migratory direction from the southwest migrating Central Europe breeding population, blackcaps breeding in britian (known to move southward via ringing), and scandinavian blackcaps who pass through brtian but do not winter there.
concordance of mean orientation b/w adult experiemental blackcaps and F1 show that a genetically programmed westerly direction which too these birds to britian was inheritded by the offspring
as well as mean direction suggest a breeding oragin b/w belgium and central germany where many west-northwest-migrants have been ringed
conclude: past 3 decades some central europeans blackcaps evolved novel migration route 1,000 - 1, 500 km north of tradational wintering areas
due to shift in genotype frequency from relaivley low to a diprptianal increase, as west to north west migratory directions fall within the normal range for genetic varitation
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starting in the 1950's and contriuning for the last 3 decades, European breeding blackcaps were found to increasingly wintering in Brtian, 1,000 - 1, 500 km north of tradational wintering areas southwest towards the meditation
the purpose of this study then was to determine if genetics was responsible for the route
reseacher's caught 20 wintering biritsh blackcaps (W.B.B) who were brought to Germany, and bred 41 "british" hand-raised offspring (B.O), they also use a control group of 49 German hand-rased offspring (G.O) that had been transfered from the wild to the rearing site.
using a modified Emlen techique they found the W.B.B adult passed on there innate migratory direction (west-northwest) to their offspring, as the mean direction was stastistically significant from both parents and offsprings compared to G.O who orentated tradnal, south west.
the similarity of mean orientation b/w adult W.B.B and B.O show that the behaviour to migrate west-northwest was genetically programmed and passed along to the offspring
the researchers suspected, the genotype that coded for the migratory route fell within the normal range, but occurred in low allele frequency in the population, however assortive mating may have played a key role in increasing the allele frequency.
I found most intresting to learn that photoperiod stimulation may be a function in assortive mating. since spring stimulaton pushes the birds to leave their wintering site earlier, the birds wintering in britain were projected to reach the breeding site 10 days ealier! This information has led me to my next article.