Ch22 Descent with modification Flashcards
What is evolution?
Descent with modification
-Darwin proposed that Earths many species are descendants of ancestrial species that were different from the present day species.
How did Aristotle view evolution?
He viewed species as fixed(unchanging). He concluded that life forms could be arranged on a ladder, or scale, of increasing complexity, later caled the scala naturae. Each life perfect and permanent, had its allotted rung on this ladder.
How did Carlous Linneaus view evolution?
Linneaus developed the two part, or binomial, format for naming species (such as Homo-Sapian for humans). Linneaus adopted a nested classification syste, grouping similar species into increasing general catagories
-Similar species are grouped into the same genus, similar genera are grouped in the same family.
What are fossils?
The remains or traces of organisms from the past which are found in sedimentary rocks formed by the sand and mud that settle to the bottom of the seas, lakes, swamps, and other aquatic habitats.
the fossil record documents the pattern of evolution, showing that past organisms differed from present day organisms and that many species have become extinct.
-Fossils also show the evolutionary changes that have occurred in various groups of organisms.
What is strata?
Superimposed layers of rock
What idea did Georges Cuvier advocate?
Catastrophism: the principle that events in the past occured suddenly and were caused by mechanisms different from those operating in the present
- Cuvier speculated that each boundary between strata represented a catastrophe, such as a flood, that had destroyed many of the species living at that time.
- He proposed that periodic catastrophes were usually confined to local regions, which were later repopulated by different species immigrating from other areas.
What did James Hutton propose regarding the earth’s geologic features?
He suggested that valleys were often formed by rivers wearing through rocks and that rocks containing marine fossils were formed when sediments that had eroded from the land were carried by rivers to the sea, where they buried dead marine organisms.
How did Chrales Lyell incorporate Hutton’s idea into his own?
By proposing his principle of Uniformitarianism, which stated that mechanisms of change are constant over time. He proposed that the same geologic processes are operating today as in the past, and at the same rate.
What ide did Jean-Baptiste de Lamark propose and why was he incorrect?
Lamark found what appeared to be several lines of descent each a chronological series of older to younger fossils. He used two principles to explain:
- )use and disuse, the idea that parts of the body that are used extensively become larger and stronger, while those that are not used deteriorate.
- ) Inheritance of acquired characteristics stated that an organism could pass these modifications to its offspring.
Lamark also believed that evolution occured because organisms have the innate drive to become more complex.
How did Darwin explain adaptation?
Adaptations are inherited characteristics of organisms that enhance their survival and reproduction in specific environments
What is natural selection?
it is a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits
Darwin accumulated evidence that descent with modification by natural selection explains what three broad observations about nature?
The unity of life, the diversity of life and the match between organisms and their environments.
How did Darwin attribute the unity of life?
He attributed the unity of life to the descent of all organisms from an ancestor that lived in the remote past. He also thought that ancestrial organisms lived in various habitats over millions of years, they accumpulated diverse modifications, or adaptations, that fit them to specific ways of life.
Why did Darwin propose the mechanism of natural selection?
To explain the observable patterns of evolution.
What is artificial selection?
The modification of species over many generations by selecting and breeding individuals that possess desired traits.
Darwin argued that an event similar occurs in nature. He based his argument on what two observations and two inferences?
observation 1: Memebers of a population often vary in their inherited traits
Observation 2: all species can produce more offspring than their environment can support, and many of these offspring fail to survive and reproduce.
Interference 1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a gien environment tend to leave more offspring than other individuals.
Inference 2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations.
How can an organisnisms heritable traits help ?
an organisms heritable traits can influence not only its own performance, but also how well its offspring copes with environmental changes.
Can individuals evolve?
Individuals do not evolve. Rather it is the population that evolves over time.
What is needed for natural selection to occur?
Natural selection can amplify or diminish only those heritable traits that differ among the individuals in a population. Thus een if a trait is heritable, if all the individuals in a population are genetically identical for that trait, evolution cannot occur.
-Natural selection is always operating, but which traits are favored depends on the context in which a species lives and mates.
Darwin accumulated evidence that descent with modification by natural selection explains what three broad observations about nature?
The unity of life, the diversity of life, and the match between organisms and their environments.
