Unit 9 - Evolution Flashcards
(27 cards)
Charles Darwin
Contributed to science through his theory of biological evolution explaining that modern organisms evolved over long periods of time through decent of common ancestors.
He also found that species are not fixed though, they have the ability to change by some natural processes (his three patterns of diversity)
Hutton and Lyll
Concluded that Earth is extremely old.
And that the processes that have changed the Earth in the past are the same processes that operate in the present.
Lamarck’s Hypothesis of Evolution
1) organisms could change during their lifetimes by selectively using or not using various parts of their bodies.
→ BUT, actually, organisms don’t have an inborn drive to become more perfect.
2) Individuals could pass these self - acquired traits on to their offspring - enabling species to change overtime.
→ BUT, actually, traits acquired by individuals during their lifetime cannot be passed onto their offspring.
OVERALL - he suggested that species are not fixed and assumed organisms inherited acquired traits.
Mathus’s View of Population Growth
Noticed mass overcrowding in the world - where people were being born faster than people were dying.
THOUGHT: If population grew unchecked, there wouldn’t be enough living space and food for everyone (which applies even more to other organisms than it does humans).
Natural Selection
The ideas that rganisms with traits more suited/ beneficial to their environment survive and produce more offspring.
NOT RANDOM**
Conditions in which Natural Selection occurs
Competition - for obtaining food, living space, and other limited necessities of life
Fitness - -how well an organism can survive (reproducing and passing adaptations on to the next generation).
Adaptation and Variation - adaptation is any heritable characteristic that increases an organism’s ability to survive and reproduce in its environment is called an adaptation which can be a result of some variations of heritable traits.
Common Descent
All species including living an extinct are descendants from common ancestors.
Evidence Used to Support Evolution - Biogeography
Biogeography: the study of where organisms live now and where their ancestors lived in the past.
→ patterns in the distribution of living and fossil species tells us how modern organisms evolved from their ancestors.
Evidence Used to Support Evolution - Fossils
Fossils: After Darwin, geologists use radioactivity to establish the age of certain rocks and fossils.
→ radioactive dating has confirmed Earth’s old age, supporting Darwin’s theory that evolution takes a while, while fossils reveal evolutionary paths, tracing the evolution of species we see today back to their common ancestors.
Evidence Used to Support Evolution - Homologous structures
Homologous structures: homologous structures are structures that are shared by related species and have been inherited by a common ancestor (Similarities among homologous structures help determine how recently species shared a common ancestor).
Evidence Used to Support Evolution -
Embryology
Similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor.
Evidence Used to Support Evolution -
Molecular Evidence (Genetics)
There is a universal genetic code is nearly identical in almost all organisms - this is powerful evidence that ALL organisms evolved from common ancestors.
Darwin’s Pattern of Diversity
Species vary GLOBALLY: Even though the animals were different, they did similar things in their ecosystems in different parts of the world that had alike environments.
Example; Rabbits and other species living in European grasslands were missing from the grasslands of South America and Australia.
LOCALLY: Different, yet related, animal species often occupied different habitats within a local area.
OVER TIME: Darwin also collected fossils - preserved remains or traces of organism. → noticing that some fossils were similar to living species and some were for organisms that no longer existed.
Analogous Structures
+ Vestigial Structures
Analogous Structures
Body parts that share common function, but not structure, are called analogous structures.
EX: The wing of a bee and the wing of a bird are analogous structures.
Vestigial Structures
inherited from ancestors but have lost much or all of their original function.
EX: Hip bones of the bottlenose dolphin
Evolution in Genetic Terms
Evolutions involves the change in the frequency of alleles in a population over time.
Gene Pool
A total of all genes in a population of organisms, including all different alleles for the particular gene.
Allele Frequency
Number of times an allele occurs in the gene pool compared to the total number of alleles in that pool for the same gene.
3 Sources of Genetic Variation
1) Mutations -
Evolution requires mutations WHICH OCCUR RANDOMLY
2) Genetic Recombination in Sexual Reproduction -
organism doesn’t inherit just one of their parents’ genes, but a combination of both so Meiosis creates gametes with DNA that is different from the parent cell.
3) Polygenic Traits -
Traits controlled by two or more genes which creates much more variation in phenotypes (ex: height).
Directional Selection
One end of the curve is higher than the other.
Stabilizing Selection
When individuals near the center of the curve have higher fitness
Disruptive Selection
When individuals at the outer ends have higher fitness.
Genetic Drift
- random change in allele frequency
Bottleneck Effect
A change in allele frequency following a dramatic reduction in the size of a population.
Founder Effect
Allele frequencies change as a result of the migration of a small subgroup of a population.
