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.
Male and Female
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).
Blanckenhorn W U , and Demont M Integr. Comp. Biol. 2004;44:413-424
The Society for Integrative and Comparative Biology
Arctic Cool Temperate Warm Temperate Desert
dark circle populations with
white circle lack cyanide
Lesser Black-backed Gull
from Davis and Heywood
Comte de Buffon Ernst Mayr
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?
Species which look almost identical morphologically but which do not interbreed.