1362-SP10-Lecture-9-_41285

1362-SP10-Lecture-9- - Microevolution Microevolution population , unitsthatcanevolve , populations&determineshow/whytheseva

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Microevolution Microevolution : heritable genetic changes that occur in a population. –N a tu r a l selection acts on individuals, but populations are the smallest nits that can volve. units that can evolve. –I n studying microevolution, one analyzes variation in natural populations & determines how/why these variations are inherited Example: change in color riants of a moth variants of a moth population What changed? hat caused this What caused this change? Macroevolution : major evolutionary events that occur over a long period, e.g., formation of a species.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Variation in Natural Populations • Populations exhibit varying degrees of phenotypic variation – Quantifying phenotypic variation uantitative : small, incremental differences qua t tat e sa , ce e ta de e c e s in a character (e.g., height,wt) Display quantitative variation in plots: Mean Low variation A lot of variation Mean qualitative : characters exist in 2 or more discreet states; ( polymorphism ) (ex: purple/white flowers of a pea plant). Quantify by calculating the fre Measurement or value of trait Measurement or value of trait quency of each trait. Average heterozygosity of a population : frequency of heterozygous loci
Background image of page 2
Variation continued & Sources of Variation • Phenotypic variation may be due to genetic Hydrangea ower color differences, environmental factors, or both. –* only heritable genetic variation is subject to volutionary change flower color (same genotype for flower color) • Selection in varying environments (geographic variation) evolutionary change • Different alleles are favored in different places, or at different times; example: variation in garden snail lor; lor ries due to habitat snail occupies acidic soil color; color varies due to habitat snail occupies. • Clines: variation in character along a geographic axis. alkaline soil • Generating genetic variation Mutation: source of new alleles; most mutations are silent or harmful; gene duplication events increase the copies of alleles. Sexual reproduction: Rearrangement of existing alleles thru independent assortment, recombination, & random fertilization.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Analysis of Populations: Hardy Weinberg Principle • Population: members of a species that inhabit an area & interbreed, producing fertile offspring. Genetic structure of a population described by its’ gene pool : – sum of all the alleles at all loci in a population Fixed allele : only one allele exists for a particular locus –I f 2 alleles at a locus Æ homozygous or heterozygous ch allele has a frequency (proportion) in the population: Each allele has a frequency (proportion) in the population: Example 500 wildflowers, 2 alleles for flower color: C R , C W ; alleles exhibit incomplete dominance; C R C R (red flowers) C W C W (white) C R C W (pink).
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/15/2010 for the course BIOL 1362 taught by Professor Loeblich during the Spring '08 term at University of Houston.

Page1 / 17

1362-SP10-Lecture-9- - Microevolution Microevolution population , unitsthatcanevolve , populations&determineshow/whytheseva

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online