EVOLUTION AND BIODIVERSITY CHAPTER 4 FACTORS effecting BIODIVERSITY

EVOLUTION AND BIODIVERSITY CHAPTER 4

FACTORS effecting BIODIVERSITY • EVOLUTIONARY PROCESSES (MICRO VS. MACRO) • MUTATIONS • NATURAL SELECTION • SPECIES FORMATION • SPECIES EXTINCTION

• EVOLUTION: change in a population’s genetic makeup • HYPOTHESES: CHEMICAL EVOLUTION VS. BIOLOGICAL EVOLUTION

Chemical Evolution (1 billion years) Formation of the earth’s early crust and atmosphere Small organic molecules form in the seas Large organic molecules (biopolymers) form in the seas Biological Evolution (3. 7 billion years) Single-cell prokaryotes form in the seas © 2004 Brooks/Cole – Thomson Learning Single-cell eukaryotes form in the seas Variety of multicellular organisms form, first in the seas and later on land First protocells form in the seas

FACTORS effecting BIODIVERSITY I. EVOLUTIONARY PROCESSES A. MICRO—small genetic changes in populations (1) MUTATIONS (some harmless, some harmful); are random and unpredictable (2) Leads to NATURAL SELECTION (3) Individuals of a popl. Have genetically based traits that increases their survival-- ADAPTATION • EXAMPLE: Peppered moth

NATURAL SELECTION “PEPPERED MOTH” Mutations/genetic changes caused natural selection to occur. Color form (2 types) was genetically based, causing greater survival due to environmental changes.

EVOLUTIONARY PROCESSES continued B. MACRO-long-term, large scale changes (1) New species formed=SPECIATION a. Caused by geographic isolation: groups of the same species become physically separated b. Caused by reproductive isolation: mutations and natural selection operate independently in two geographically isolated populations » So different, can’t breed or produce live young » One species becomes two through divergent evolution

ØSpeciation… Early fox population Spreads northward and southward and separates Northern population Arctic Fox Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage. Different environmental conditions lead to different selective pressures and evolution into two different species. Southern population Gray Fox leads to…. Geographic isolation and Reproductive isolation Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat.

EVOLUTIONARY PROCESSES continued (2) Species Extinction (a) if species can’t adapt, move, or cease to exist when environmental conditions change (b) causes of extinction habitat loss, overhunting, invasive species

Other factors relating to adaptations to the environment • Ecological niche – “way of life” or functional role a species plays in it’s environment – different from habitat (physical location) – 2 categories: (1) Generalist species: broad niches – – eat a variety of foods, wide range of tolerance ex: cockroaches, mice, rates, raccoons, coyotes, humans

(2) Specialist species: narrow niches • Live in only 1 habitat type • Eats specialized food • Narrow range of tolerance • Prone to extinction • Ex: spotted owls, giant panda, koala