Flashcards
Macroevolution
Flashcards do conjunto (20)
- 1Microevolutionsmall phenotypic changes in populations over a relatively short period of time. Evolution within species.
- 2Macroevolutionlarge phenotypic changes within lineages across higher taxa over a long period of time.
- 3Gradualism(Darwin) evolutionary change within lineages is slow and continuous.
- 4Punctuated Equilibriumevolution within lineages occurs in short periods with rapid change separated by long periods with little or no change.
- 5Stasislittle or no evolutionary change over a long period of time
- 6What Causes Stasis?1. Developmental Canalization
2. Stabilizing Selection
3. Habitat Tracking
4. Gene Swapping - 7Developmental CanalizationThe evolution of internal factors during development that reduce the effect of perturbing environmental and genetic influences, thereby constraining phenotypic variation.
- 8Stabilizing Selectionphenotypic variation in a population is usually centered around an adaptive peak where fitness is optimal. Therefore, stabilizing selection will maintain a constant average phenotype.
-Assumes little or no environmental change. - 9Habitat Trackingwhen the environment changes, the average phenotype remains constant because the geographic distribution of the species shifts so that its “effective environment” remains constant.
- 10Gene Swappinggene flow among populations impedes novel adaptations to local environments.
-Major evolutionary change requires reproductive isolation - 11Speciationlarge evolutionary change over a short period of time
- 12What Causes Rapid Change?1. Allopatric Speciation by Dispersal
2. Saltation
3. Rapid Microevolution - 13Allopatric Speciation by Dispersalthe founder effect and genetic drift in a small population leads to a breakdown of coadapted gene complexes and a “genetic revolution”.
- 14Saltationmutations with large phenotypic effects give rise to “hopeful monsters” adapted to new ways of life.
- 15Rapid Microevolutionecent studies have revealed significant changes within populations over short periods of time.
- 16Passive Trendrandom change bounded on one side
-Graph - 17Active Trendnonrandom change driven by natural selection
- 18Species Selection for an Active TrendGraph
- 19Cope’s Rule . -change within genera -Example of Horse Lineageincreased body size within lineages over time.
-RESEMBLES A PASSIVE TREND
-RESEMBLES AN ACTIVE TREND
-K-selection should increase body size, but r-selection should decease body size - 20The effects of individual and species selection on body size -Case Study-Individual selection may increase body size, but large species may be more prone to extinction
-Blaire Van Valkenburgh (2004) on Cope’s rule and extinction in mammals:
-Over the past 50 million years, successive clades of large carnivorous mammals diversified and then declined to extinction.
-Pervasive selection for larger size in carnivores lead to dietary specialization and increased vulnerability to extinction.
-Thus, selection for attributes that promoted individual success resulted in progressive evolutionary failure of their clades.
Informações
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- Evolution 100 FlashCards sobre Macroevolution, criado por cjangeles em 09-09-2014.
- Criado por
- cjangeles
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