Download Spartina

Evolutionary Ecology
Evidence of local adaptation
Environmental or Genetic
Variation in WesternYarrow?
Creeping Bent Grass - Agrostis stolonifera
Adaptation in Trinidad Guppies
Poecilia reticulata
Male and Female
Two males
Adaptation and natural selection in
guppy populations
John Endler
Cline – Bergmann’s Rule
Bergmann’s Rule in Bears
Sun bear, Spectacled bear, Brown bear, Polar bear
Fig. 3. Mean ± SE body size (top) and egg to adult development time (bottom) as a function
of latitude for lab-reared families of yellow dung fly males and females from six different
latitudinal populations in Europe, at 15°C in the sequential experiment (CH: Switzerland; GB:
England; D: Germany; S: Sweden; ISL: Iceland).
The Society for Integrative and Comparative Biology
Blanckenhorn W U , and Demont M Integr. Comp. Biol.
2004;44:413-424
Cline – Allen’s Rule
Arctic
Cool Temperate Warm Temperate
Desert
White clover – Trifolium repens
Cline in
cyanide
production
by white
clover –
dark circle
populations
with
cyanide;
white circle
lack cyanide
Clinal variation in gulls
Herring Gull
Lesser Black-backed Gull
What is a species?
Morphological species concept:
• Assemblages of individuals with
morphological features in common and
separable from other such assemblages by
correlated morphological discontinuities in
a number of features.
from Davis and Heywood
Rubus - Blackberries
Biological Species Concept
Comte de Buffon
Ernst Mayr
Biological species concept
A species consists of a groups of organisms which
can sexually interbreed or at least have the
potential to sexually interbreed (if geographically
isolated) that are reproductively isolated from
other such groups.
This is based on two criteria:
1. do populations from the same locality normally
interbreed?
2. if cross-fertilization does occur, are the hybrids
viable and fertile?
Sibling species
Species which look almost identical morphologically
but which do not interbreed.
Drosophila pseudoobscura
Gilia tricolor
Gilia angelensis
Polytypic species
• Species made up of populations which
differ morphologically but which will
interbreed in nature.
Variation in Song Sparrows
Potential problems with biological
species concept
• Fossil species cannot be tested for
reproductive isolation
• Asexual species also cannot be test for
reproductive isolation – each clone is
genetically separate from all others – Mayr
calls asexual species ‘paraspecies’
Phylogenetic species concept
• Species are defined based upon branching
patterns in phylogenetic trees. Species are
also defined based upon differences in
evolutionary history. Species typically
diverge when reproductively and/or
geographically isolated.
Western and Florida Scrub Jay
Speciation
• Speciation is the formation of new species.
• Allopatric speciation - formation of new species
occurs when populations of a species become
geographically separated from each other and
diverge so that when they co-occur they cannot
interbreed.
• Sympatric speciation - occurs when reproductive
isolation occurs within the range of a population
before any differentiation of the two species can
be detected.
Allopatric Speciation –
Galapagos Islands Finches
Darwin’s
Finches
Sympatric and Allopatric Speciation –
Picture Winged Drosophila
Eight
Species of
PictureWinged
Drosophila
Founder Events with Picture
Winged Drosophila
Sympatric Speciation in Cichlids
Variation in Lake Malawi and
Lake Tanganyika Cichlids
Polyploidy in Spartina cordgrasses
• Polyploidy - an increase in the number of
chromosomes beyond the typical diploid
number - may be a doubling or greater - this
happens most often in plants
• Polyploidy often occurs following the
production of hybrids
Spartina alterniflora marsh – North Carolina
Spartina
alterniflora
Spartina
maritima
Spartina x townsendii
Spartina
anglica
Spartina anglica – invasive in New Zealand