E1. Populations are the units of communities.

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Presentation transcript:

E1. Populations are the units of communities.

E1.1 Know that a community is made up of localised, interacting populations.

Key terms individual population community ecosystem abiotic biotic

E1.2 Explain that populations in a community consist of different species, and know the characteristics that define a species.

Species members of populations interbreed or potentially interbreed fertile offspring gene flow is prevented or limited

Appearance isn’t everything identical appearance ranges overlap distinct songs prevent interbreeding separate species Western meadowlark Eastern meadowlark

Appearance isn’t everything Sexual dimorphism Pheidole barbata Scarce Vapourer - Orgyia recens Indian peacock - Pavo cristatus

E1.3 Give examples of mechanisms that maintain the reproductive isolation of species in a community.

Reproductive barriers between species Habitat - different locations Behavioural - mating rituals, no attraction Temporal - timing of mating, flowering Mechanical - structural differences Gametic - gametes fail to unite Hybrids die in development, are weak or infertile

Courtship ritual in blue-footed boobies is an example of behavioural isolation Many plant species have flower structures that are adapted to specific pollinators mechanical isolation Figure 14.2A, B

Hybrid sterility is one type of postzygotic barrier A horse and a donkey may produce a hybrid offspring, a mule Mules are sterile

If reproductive barriers are overcome we get HYBRIDS

Female tiger X Male lion

LIGER

X Female lion Male tiger

TIGON

Pony X Horse Zebra Donkey

ZONY ZEBROIDS ZORSE ZONKEY

X Polar Bear Grizzly Bear

GROLAR/PIZZLY BEAR

GROLAR/PIZZLY BEAR Generally hybrid animals only occur within captivity as there are many reproductive barriers to isolate the two species. Polar bear – living in ice/water & breeding on ice Grizzly bear – living and breeding on land Theory 1: interbreeding has always happened Theory 2: melting of ice caps causes migration

Llama X Camel

CAMA

canis lupus familiaris subspecies of the grey wolf various breeds same subspecies