Studied by 48 peopleEvolution
The relative change in the characteristics (genetic traits) of a species over several generations and relies on the process of natural selection.
Microevolution
Evolution on a small scale. The gradual change in allele frequencies (genes) in a population over a short period of time. Results in subtle changes to a species that may not be observable to the casual observer.
Macroevolution
Evolution on a large scale. Involves evolutionary patterns and changes above the species level. Happens over a longer period of time. Results in the evolution of new species and brand new groups of organisms.
Adaptation
A structural, behavioral, or physiological trait that helps an organism survive and reproduce in its environment. Are the result of gradual changes in genetic traits in members of a species over time.
Variation
A visible or invisible difference among some members of a population. As they become more common, they become described as traits within that population.
Selective Advantage
Any characteristic that improves an organism’s chance of survival within its environment. Heritable variations that help an individual survive are an example.
Natural Selection
The process which results when the characteristics of a population of organisms change because individuals with certain inherited traits survive specific local environmental conditions and, through reproduction, pass down their traits to their offspring. It requires variation and diversity within species.
Selective Pressure
The environment exerts this on species which in turns selects certain characteristics of individuals - drives competition.
Georges-Louis Leclerc
One of the first to openly challenge the idea life forms are unchanging. He published Histoire Naturelle. Speculated that humans and apes might have common ancestry.
Mary Anning
Pioneer of paleontology. An English fossil collector famous for her discoveries in Jurassic marine fossil beds in the cliffs along the English Channel. Her fossil discoveries, like that of Ichthyosaurus, forced people to widely question the idea that all life came into existence at the same time and had never changed.
Georges Cuvier
Credited with developing the science of paleontology. Found that each stratum (layer of rock) was characterized by a unique group of fossil species - deeper (older) stratum, the more dissimilar the species are from modern life. He found evidence that new species appeared and others disappeared - illustrating the possibility of extinction. Also proposed the idea that Earth experienced many destructive natural events. These catastrophic events were violent enough to have killed numerous species and change the geological landscape of Earth - catastrophism
Charles Lyall
Rejected the idea of catastrophism. Proposed that geological processes operated at the same rates in the past as they do today; slow and continuous - uniformitarianism.
Jean-Baptiste Lamarck
Wrote Philosophie Zoologique which documented changes in species over time. Discussed progression in which a series of fossils (from older to more recent) led to a modern species. Discussed that idea that species increased in complexity over time. Famous for proposing the concept of inheritance of acquired characteristics. Noted that an organism’s adaptations to the environment resulted in characteristics that could be inherited by offspring.
Charles Darwin
Was a naturalist. It was in the Galapagos Islands where he is famous for making his observations - most notably Darwin’s Finches - which would ultimately be discussed in his book - On the Origin of Species.
Alfred Wallace
Was a naturalist who independently reached conclusions similar to Darwin. He was close to an explanation of evolutionary thought for life on Earth.
Thomas Malthus
Proposed that populations produce more offspring than their environments could support and were eventually reduced to starvation and disease. Suggesting that there would also be survivors.
Paleontology
The study of the history of life on Earth as based on fossils.
Inheritance of Acquired Characteristics
The idea that characteristics that a species acquired during an organism's lifetime could be passed on to its offspring.
Artificial Selection
Selective breeding to obtain varieties of plants or animals with desired traits. Traits we want to reproduce and those we don’t are actively selected for continuation or removal.
Fossil Record
Defined as the remains or traces of past life preserved in sedimentary rock, which reveal the history of life on Earth.
Relative Dating
Fossil species that are known to be common during a certain time period can be used to index fossils. These indicate the approximate age of the rock they were found in.
Radiometric Dating
Uses measurements of radioactive isotopes to calculate the absolute age in years of rocks and minerals. Radioactive isotopes decay, knowing how long they decay by half of their original amount allows for absolute calculations.
Transitional Fossils
Defined as fossils that show intermediary links between groups of organisms. Important as they help to fill gaps in the fossil record.
Biogeography
The study of the past and present geographical distributions of different types of organisms.
Homologous Structures
Are structures that have similar structural elements and origin but may have different functions. Keep in mind that functional similarity does not necessarily mean that species are closely related.
Analogous Structures
Physical features that evolved separately but perform similar functions in different types of organisms. Structures evolved independently to serve the same purpose.
Convergent Evolution
This tendency (evolutionary trend) among species that are not closely related to develop similar body plans when living under similar conditions.
Vestigial Structures
Some species have anatomical features that serve no function. Anatomical features that no longer retain their function.
Comparative Embryology
Embryos are the early stages of development in multicellular sexually reproducing organisms. Generally begins after fertilization and continues through the formation of body structures.
Speciation
Defined as the formation of new species. There are two general pathways that can lead to: Â transformation and divergence.
Transformation
Is speciation which occurs when a new species replaces the old. It does not increase the total biological diversity of species on Earth.
Divergence (Aka. Adaptive Radiation)
Is speciation where one or more species arise from a parent species that continues to exist. It does increase the total biological diversity on Earth.
Geographical Barriers
Any geographical element (river, mountain, etc.) of Earth that physically separates populations from interbreeding.
Biological Barriers
Aka. Reproductive Isolating Mechanisms. Any biological/physiological attribute of a population that keep them reproductively isolated from other populations, even if they exist in the same geographic area. There are two types Pre-Zygotic and Post-Zygotic.
Pre-Zygotic
Are barriers that prevent organisms from different species from mating.
Behavioral Isolation
Refers to species-specific signals or behaviors that prevent interbreeding with closely related species.
Habitat Isolation
A biological barrier in which different species live in the same area, but they use different habitats, and so rarely encounter each other.
Temporal Isolation
Timing barriers that prevent species in the same habitat from interbreeding. Species may mate or flower at different times of the day, different seasons, or in different years.
Mechanical Isolation
A biological barrier in which closely related species have incompatible reproductive structures.
Gametic Isolation
A biological barrier that prevents eggs and sperm from different species fusing to form a zygote.
Post-Zygotic
Barriers that prevent hybrid zygotes from developing into viable, fertile, adults.
Hybrid Inviability
A genetic incompatibility of interbred species that stops development of the hybrid zygote during its development.
Hybrid Sterility
A biological barrier that exists between two species because, although they can mate and produce hybrid offspring, the offspring are sterile.
Hybrid Breakdown
A biological barrier that occurs when first-generation hybrids, which are fertile, mate with each other or with an individual from either parent species, and the offspring are either sterile or weak.
Adaptive Radiation
Speciation where one or more species arise from a parent species that continues to exist.
Coevolution
The process of reciprocal evolutionary change that occurs between pairs of species or among groups of species as they interact with each other.
Gradualism
Describes evolution as slow, steady, and linear with the accumulation of many small changes producing large changes.
Punctuated Equilibrium
Describes evolution as consisting of long periods of stasis, interrupted by periods of rapid change. Rapid changes are often the result of mass extinctions.
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