Topic 2

The development of an egg with no paternal contribution - female clonal reporduction; “virgin birth” • Obligate parthenogenesis • Cyclical parthenogenesis

only females exist (in species), eggs never develop into males and there is never sexual reproduction

Males develop from eggs at some point, resulting in sexual reproduction, and this reporduction produces an all female population that reproduces clonally

1.Morphological species concept: Indiv are considered to belong to the same species if they agree morphologically with the “type” of the specis • Biological Species concept: species are groups of interbreeding natural populations that are reproductively isolated from other such groups • Phylogenetic species concept not covered in this class

Indiv are considered to belong to the same species if they agree morphologically with the “type” of the specis

species are groups of interbreeding natural populations that are reproductively isolated from other such groups (only works for sexually reprod. pop’n, not for asexual)

• Natural selection: heterozygote excess/deficit • Inbreeding: heterozygote deficits • outbreeding: heterozygote excess • assortative mating: heterozygote excesses or deficits • asexual reproduction: heterozygote excesses or deficits • cryptic species: heterozygote deficits • gene flow ad migration: heterozygote excesses or deficits

sex determination: e.g. in humans, males have only 1 X chromosome vs females have 2 (Y chromosome only carries few genes)

X-linked genes

sex which produces two of the same gametes (e.g. females produces 2 X in humans)

sex which produces two different gametes (eg. male produces X and Y gametes) Note: in some groups e.g. birds, moths and butterflies, females are heterogametic (W and X)

sex which produces two of the same gametes (e.g. females produces 2 X in humans)

sex which produces two different gametes (eg. male produces X and Y gametes)