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Natural selection The process by which traits become more or less common in a population through differential survival and reproduction.

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Presentation on theme: "Natural selection The process by which traits become more or less common in a population through differential survival and reproduction."— Presentation transcript:

1 Natural selection The process by which traits become more or less common in a population through differential survival and reproduction

2 Adaptive radiation A form of divergent evolution in which there is rapid speciation of one ancestral species to fill many different ecological niches

3 Evolution is not perfect Selection can act only on existing variations Evolution is limited by historical constraints Adaptations are often compromises Chance, natural selection, and the environment interact

4 1. Direct observation 2. The fossil record 3. Homology 4. biogeography Identify the 4 major types of evidence to support the theory of evolution.

5 .49.59.41 A population of rabbits may be brown (the dominant phenotype) or white (the recessive phenotype). Brown rabbits have the genotype BB or Bb. White rabbits have the genotype bb. The frequency of the BB genotype is.35. What is the frequency of heterozygous rabbits? What is the frequency of the B allele? What is the frequency of the b allele?

6 Founder effect Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original position

7 Sexual dimorphism Marked differences between the two sexes in secondary sexual characteristics, which are not directly associated with reproduction or survival

8 Speciation in which the populations are physically separated. A term for physically separated populations. Allopatric

9 species Group or population of individuals that can interbreed to produce viable offspring

10 Homeotic gene Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells

11 Reduced hybrid viability The genes of different parent species may interact in ways that impair the hybrid’s development or survival in it’s environment

12 Convergent evolution The evolution of two or more lineages towards similar morphologies or adaptations so that the lineages appear similar despite their different ancestry

13 homology Similarity between species that results from common ancestry

14 Vestigial structures Structures that have apparently lost all or most of their original function in a species through evolution

15 speciation The division of one species, during evolution, into two or more separate species

16 Punctuated equilibrium Periods in the fossil record of apparent stasis punctuated by sudden change

17 Phylogenetic species concept A species is the smallest group of individuals that share a common ancestor, forming oine branch on the tree of life

18 Gene flow Genetic exchange between populations tends to reduce differences between populations over time.

19 Identify 5 conditions to maintain Hardy Weinberg Equilibrium No mutations Random mating No natural selection Extremely large population No gene flow

20 Bottleneck effect Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population

21 Temporal isolation Species that breed during different times of the day, different seasons, or different years cannot mix their gametes

22 Morphological species concept A species is characterized by structural features Can be applied to sexual and asexual organisms

23 evolution Changes in gene pools over time

24 mutation the ultimate source of new alleles

25 Hybrid breakdown Some first generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile

26 Jean-Baptiste de Lamarck Use and disuse Inheritance of acquired characteristics

27 Intersexual selection Selection whereby individuals of one sex are choosy in selecting their mates from individuals of the other sex Also called “mate choice”


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