Changing habitats, changing populations?

Changing habitats,changing populations?

Life-history evolution of coexisting Drosophila species in a heterogeneous

environment.

Kim van der Linde ,Institute for Evolutionary and Ecological Sciences,Section Animal Ecology and Section Evolutionary Biology,Leiden University, The Netherlands.

10 dec 1998 Changing habitats, changing populations?

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Changing habitats, changing populations?

• Darwin finches (Grant & Grant)Beaksize variation between generations is correlated with size of available seed.

• Guppies (??)Life-history strategies vary with predator. Transplantation to other stream with other predator induces evolution to the other strategy.

• ???Add self more examples!


3

A life history trade off and community structure in a variable environment.

Sevenster JG & van Alphen JJM (1993) J. Anim. Ecol. 62: 720-736.

• The environment is variable through the year.

• Species differ in life-history.

• A short development time is an advantage when fruit is abundant.

• A long survival time under food stress is an advantage when fruit is scares.

• A physical trade-off between development time and starvation resistance make that different species have a competitive advantage during different times of the year!


4

Changing habitats

• Changes in: – vegetation structure

– fruit availability

– temperature

– humidity

– ….


5

Which traits?

• Ecological important traits:– Development time

– Starvation resistance• Life-history model of Sevenster & van Alphen (1993)

– Body size

– Egg size (Relative egg size)• Extension to the model by Toda & Kimura (1996)


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Different habitats

• Habitats differ in year round breeding substrate availability.

• Local populations are likely to adapt to those differences.

• Expected result is that populations from different habitats from the same species will show differences in the life-history traits.


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Philippines 1994

• Collecting flies from four habitats: secondary forest, forest edge, kaingin and grassland.

• Bring them to a common environment of the lab.

• Measuring development time and starvation resistance.


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Development timesPopulation development times

7.00

7.50

8.00

8.50

9.00

9.50

10.00

10.50

11.00

11.50

Av

era

ge

de

v.

tim

e (

da

ys

)

Forest edge 9.50 8.69 9.59 9.94 8.53

Grassland 9.74 11.01 8.44 9.61 9.75

Kaingin 8.97 8.67 8.23 8.50 8.72 8.83

Secondary forest 8.21 8.51 8.29 10.08 8.50

D. ananassae D. atripex D. bipectinata D. eugracilis D. malerkotlianaD.

pseudoananassae

D. sulfurigaster D. takahashii


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Starvation resistancesPopulation starvation resistances

0

0,5

1

1,5

2

2,5

3

3,5

Sta

rva

tio

n r

es

ista

nc

e (

da

ys)

Forest edge 1,5 2,68 1,92 3,18 2,29

Grassland 1,98 1,27 2,2 1,42 2,91

Kaingin 1,9 2,45 2,05 2,25 1,9 2,56

Secondary forest 2,08 1,84 2,04 2,79 1,83

D. ananassae D. atripex D. bipectinata D. eugracilis D. malerkotlianaD.

pseudoananassae

D. sulfurigaster D. takahashii


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Conclusions and questions

• Habitat related variation between populations in development time.

• Variation is of same pattern for all (7) species of the Sophophora subgenus.

• But what are the realized values in the field?

• Are some or all traits genetically correlated?


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Common environment versus real environment

Common environment versus real environment

7,007,508,008,509,009,50

10,0010,5011,00

1 2 3 4

Habitat

De

ve

lop

me

nt

tim

e

Found in common environmentSmoothening effect of realityAmplified effect of reality


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Genetic correlation's in D. melanogaster

Development time

Body size

Longevity

Starvaton resistance / fat content

+

+ +00

±0

Source: Zwaan, BJ (1993) Genetical and environmental aspects of aging in Drosophila melanogaster. Ph.D. thesis, Groningen


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Questions after that

• Does natural selection shape the life-history traits even throughout the year?

• E.g. are there differences within flies collected in different times of the year?


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Panama 1998

1 Expression of life-history traits in the original habitat

2 Transplantation experiment, offspring of many females

3 Transplantation experiment, offspring of a single female


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Transect 1 Transect 2


Hab. A Hab. B Hab. C Hab. A Hab. B Hab. C

Experiment 1


Allstocks

Allstocks

Allstocks

Allstocks

Allstocks

Allstocks


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Hab. A Hab. B

Hab. A oftransect 1

Species 1of Hab. A

Replica 1Replica 2Replica 3

Species 2of Hab. A


Species 1of Hab. B


Species 2of Hab. B


Species ..of Hab. B

Species 3..of Hab. A

Hab. A

Hab. B

Experiment 2

Hab. C

Hab. C


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Transect 1

Hab. A Hab. B

Hab. A

Species 1of Hab. B


Species 2of Hab. B


Experiment 3

Species 3of Hab. B


Species 1of Hab. B


Species 2of Hab. B


Species 3of Hab. B


Species 1of Hab. B


Species 2of Hab. B


Species 3of Hab. B


Species 1of Hab. B


Species 2of Hab. B


Species 3of Hab. B


Species 1of Hab. B


Species 2of Hab. B


Species 3of Hab. B


Species 1of Hab. A


Species 2of Hab. A


Species 3of Hab. A


Species 1of Hab. A


Species 2of Hab. A


Species 3of Hab. A


Species 1of Hab. A


Species 2of Hab. A


Species 3of Hab. A


Species 1of Hab. A


Species 2of Hab. A


Species 3of Hab. A


Species 1of Hab. A


Species 2of Hab. A


Species 3of Hab. A


Transect 1

Hab. A Hab. B

Hab. C

Transect 2

Hab. A

Hab. B

Hab. C


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Experiment 2& 3

Stocks

Expe-riment

Documents

Changing habitats, changing populations?