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Lamarckism
Jean-Baptiste Lamarck proposed that organisms change during their lifetime in response to their environment and pass these acquired traits to their offspring. This idea suggests that evolution occurs through the inheritance of acquired characteristics, which is now known to be incorrect
Darwinian Evolution (natural selection)
Charles Darwin proposed that within a population, variations exist randomly, and individuals with traits that provide a survival advantage are more likely to survive and reproduce. Over generations, beneficial traits become more common, leading to evolutionary change
what are the two mechanisms for evolution
Lamarckism and Darwinian Evolution (natural selection)
evolution
the cumulative change in the heritable characteristics of a population over time.
evolution in Lamarckism
suggests that traits acquired during an organism’s lifetime are inherited by offspring
evolution with Darwinism
argues that evolution occurs due to natural selection acting on heritable variations, with advantageous traits becoming more frequent over generations.
Hox Genes
control body plan development in animals, and their simmilarities across different species suggest a common evolutionary ancestry.
example of Hox genes
The presence of similar hox genes in jellyfish, segmented worms, insects, and vertebrates supports the idea that they share a distant common ancestor
How can DNA, RNA and amino acid sequences be used as evidence for evolution?
Th elmore closely related two species are, the fewer differences they have in their DNA and RNa base sequences or their amino acid sequences
Selective Breeding
(artificial selection) is when humans choose specific traits in animals or crops and breed individuals that exhibits those traits. Over successive generations, this leads to significant changes in a species.
Homologous structures
anatomical features that have a similar structural arrangement but serve different functions in different species
example of homologous structures
The pentadactyl limb found in vertebrates
what is adaptive radiation?
when one species rapidly diverges into multiple species, each adapted to a different environment.
example of adaptive radiation?
Darwin’s finishes evolved different beak shapes suited to different food sources.
analogous structures
features that serve the same function but have different structures and evolutionary origins
examples of analogous structures
wings of birds (feather and bone) vs wings of insects (chitin)
differences between Homologous and Analogous structures
homologous structures have a common ancestor but difference functions while analogous structures have the same function by evolved independently
speciation
the formation of a new species due to reproductive isolation and genetic divergence.
example of speciation
bonobos and chimpanzees evolved into separate species after being geographically isolated by the congo river.
why is gradual evolutionary change in species not speciation?
gradual evolutionary change (continuous variation) within a species does not necessarily result in speciation unless enough genetic differences accumulate to prevent interbreeding.
reproductive isolation
occurs when two populations can no longer interbreed, leading to the formation of new species.
geographic isolation
happens when a physical barrier like a river seperates populations, preventing gene flow and slowing them to evolve independently
natural selection
process when individuals who are better adapted to their environment are more likely to survive and reproduce than other member of the same species
3 ways to get genetic variation
mutation (changes in DNA sequence), gene flow (movement of alleles between interbreeding populations), and sexual reproduction
How did Charles Darwins theory of evolution cause a major paradigm shift?
fundamentally changing the prevailing scientific understanding of life on earth, moving away from the idea of fixed species created by a divine being and instead establishing the concept that all living organisms are interconnected and have evolved over time through natural selection.
carrying capacity
the population size that can be supported by the environment.
density dependent
ecological process that describes how population growth is affected by population density
density independent
environmental factors that affect a population regardless of the populations density. ex: low temperature
fitness
how well adapted a individual is. the fitters individuals tend to survive longer and have the most offspring—larger contribution to gene pool.
abiotic factors
comes from non living things
biotic factor
comes from living things
selection pressures
external agents which can affect an organisms ability to survive in a given environment.
sexual selection
animals with distinctive physical characteristics or behaviors may have a easier time acquiring mates. ex: peacocks
how is complexity and variation between organisms the basis for having a classification system?
no two individuals are identical. The patterns of variation help scientist organize and name organisms systematically. this allows for identifying relationships, understanding evolutionary history, and categorizing organisms based on similarities and differences.
what are the three domains of life
Archaea, Eubacteria, and Eukarya
Eukarya
uni- or multicellular organisms grouped into four kingdoms—Animalia, Plantae, Fungi, and Protista
Eubacteria
prokaryotic, single-celled organisms that live in various environments and can perform photosynthesis
Archaea
prokaryotic, single-celled organisms that can survive in extreme environments
Morphological Species Concept
Linnaeus classified species based on shared physical traits such as shape and size. He described approximately 5,900 species using this method. This approach suggests species don’t change over time (not accurate)
biological species concept
a species is defined as a group of organisms that can interbreed and produce fertile offspring.
Taxa in Linnaeus Classification system
Domain, kingdom, phylum, Class, order, family, genus, species
binomial nomenclature rules
the genus is capitalized the species is lowercase, and names are italicized when typed or underlined when handwritten
why is it difficult to distinguish between populations and species
if two populations of a species stop interbreeding they may gradually evolve into separate s[ecoes. This gradual divergence makes it hard to define when a population has become a distinct species.
diversity in chromosome numbers among species
different plant and animal species exhibit varying chromosome numbers. chromosomal changes such as fusions, splits, or duplications occur over millions of years. ex: primates had 48 chromosomes but humans evolutions resulted in 46.
karyotyping and human-Chimpanzee Similarities
Human chromosome 2 appears to be a fusion of chimpanzee chromosome 12 and 13. similar banding patterns, chromosome lengths, and centromere positions support this hypothesis.
single nucleotide polymorphism
variations in a single DNA nucleotide that occur in under 1% of a population
how single nucleotide polymorphism shows unity and diversity in a species.
while maintaining a shared genetic framework.
describe how genome size and base sequence varies between eukaryotic species.
genome size varies wildly among species, larger genome size does not necessarily mean greater complexity, differences in base sequences lead to species variation, even among closely related organisms
