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Biology 108
| Term | Definition |
|---|---|
| Biological diversity | the variety of life on Earth ->2 million species on Earth, Estimates on the true number of species vary (ranges from 5 to 100 million). |
| Genetic diversity | The genetic variation within a population and between populations within a species |
| Species diversity | All the variety of species of animals, plants, fungi, and micro-organisms that occur in an area. |
| Ecosystem diversity | The variety of different habitats in a region, and their patterns and linkages across the landscape |
| Ecosystem services | Four types: Provisioning, Regulating, Supporting, and Cultural services |
| Provisioning services | The products we obtain from nature including our food, raw materials, medicine, energy, water, and genetic resources. |
| Regulating services | The benefits humans receive beyond raw materials, such as climate regulation, purification of water and air, pollination, and pest control |
| Supporting services | Critical to biosphere viability. Examples include oxygen production, absorption of CO2, etc. |
| Cultural services | The intangible, non-material benefits people obtain from nature and ecosystems |
| Extinction | A species is considered extinct when it exists nowhere on the globe. |
| Extirpation | A species is considered extirpated when it no longer exists in a defined geographic region but can be found elsewhere |
| Habitat loss | Human alteration of habitats is the greatest threat to biodiversity. In almost all cases habitat loss and fragmentation lead to loss of biodiversity. |
| Invasive species | An introduced species that negatively impact environment, economy, or society. Examples include zebra mussels, brown tree snake, etc. |
| Overexploitation | Human harvesting of wild plants or animals at rates exceeding the ability of populations of those species to recover. Examples include overfishing, poaching, etc. |
| Global climate change | The climate is changing more rapidly than ecosystems and species can adjust. |
| Taxonomy | The scientific discipline concerned with naming and classifying organisms. |
| Linnaean system of nomenclature | Hierarchical classification of species into groups based on the similarity of structure, function, and other features. |
| Linnaean classification | Groups species into increasingly broad categories, based on the degree to which they share characteristics. Major taxonomic ranks(broad to narrow): domain, kingdom, phylum, class, order , family, genus, species. |
| Systematics | The theory of classifying organisms based on evolutionary history. Attempts to construct evolutionary informative classifications |
| Phylogeny | The evolutionary history of a species or group of related species. |
| Phylogenetic tree | Show hypotheses for the evolutionary relationships between extinct and living organisms as lines of evolutionary descent of different species, organisms or genes from common ancestors. inferred from morphological and molecular data. |
| Morphological data | The size, shape, and presence/absence of different anatomical features. |
| Molecular data | Molecular systematics uses DNA, RNA, and protein structures to infer phylogenies. |
| Basal taxon | The first taxon to diverge in the history of a group and originates near the common ancestor of the phylogeny. |
| Polytomy | A branch from which more than two groups emerge. |
| Clade | A piece of a phylogeny that includes an ancestor and ALL descendants of that ancestor |
| Cladogram | Depicts evolutionary relationships where only the pattern of branching is important. |
| Phylogram | Also depicts evolutionary patterns, but branch lengths are proportional to evolutionary change. |
| Homology | Similarity due to shared ancestry (shared evolutionary origin) |
| Analogy | Similarity due to convergent evolution. (convergent evolution is independent evolution of similar traits in different lineages) |
| Ingroup | The group of taxa whose evolutionary relationships you are interested in determining. |
| Outgroup | One or more taxa that are related to the ingroup, but that have diverged from the ingroup at an earlier time. |
| Characters | Anatomical, physiological, or molecular features of organisms. |
| Character state | The observed manifestation of that character. |
| Cladistics | A method of inferring phylogeny from homologous characters. |
| Monophyletic group | Consists of an ancestor taxon, all its descendants, and no other unrelated taxa. |
| Paraphyletic group | Consists of an ancestral taxon, but not all of the descendants. |
| Polyphyletic group | Includes distantly related taxa but does not include the common ancestor of all group members |
| Synapomorphy | A shared, deprived character. It's shared by two or more taxa and their most recent common ancestor but is not found in the ancestor that precedes the clade. |
| Symplesiomorphy | A shared, ancestral character. It's an ancestral character shared by two or more taxa, including taxa in an earlier clade. |
| Natural selection | The process in which individuals with favorable inherited traits are more likely to survive and reproduce at higher rates bc of those traits. no natural selection without selective pressures. Causes adaptive evolution. |
| Descent with modification | All organisms are related through descent from an ancestor that lived in the past. describes speciation (The origin of new species). |
| Genotype | The genetic make up of an organism (complete set of genes). |
| Genotypic (genetic) variation | The difference in DNA among individuals in populations. It is heritable, The traits or variants encoded in DNA are passed from parent to offspring during reproduction. Arises randomly in populations |
| Phenotype | An organism's observable characteristics. Determined by interaction of environmental factors and its genotype. |
| Phenotypic variation | The variability in phenotypes that exists in populations. |
| Selective pressure | Consistent selection pressure leads to a directional change in the population, if it changes the direction of natural selection changes. |
| Selective agents | Environmental factors acting on populations to effect the survival and/or reproduction of individuals in the populations. When a selective agent consistently causes differences in survival and/or reproduction in a population, it's a selection pressure. |
| Adaptation | An inherited characteristic of an organism that enhances its survival and reproduction in a specific environment. |
| Comparative Embryology | It reveals anatomical homologies that are visible only during embryonic development. |
| Molecular homology | Genes shared among organisms inherited from a common ancestor |
| Vestigial structures | Reduced or non-functional features that served important functions in an organisms ancestors. |
| Biogeography | The study of the geographic distribution of organisms and is based on both living species and fossils |
| Endemic species | Species that are only found in a specific area and are not found elsewhere on earth. |
| Microevolution | The change in allele frequencies in populations over generations. |
| Relative fitness | The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals. |
| Directional selection | Favors individuals that differ from the current mean phenotype phenotype of a population in one direction |
| Disruptive selection | Favors individuals at both extremes of the phenotypic range. |
| Stabilizing selection | Favors intermediate or common variants by selecting against extreme phenotypes that deviate the current population mean. Conserves functional genetic features by selective pressure against deleterious variants. |
| Genetic drift | Random changes in allele frequency in a population, more likely in small population. |
| Bottleneck effect | A sudden reduction in population size due to a change in the environment. Allele frequency in the next generation is different than the previous generation. |
| Founder effect | Occurs when a few individuals become isolated from a larger population. |
| Gene flow | The movement of alleles between populations of a species, can introduce new variation into the receiving population, reduces variation between populations over time. |
| Neutral variation | Genetic variation that does not confer a selective advantage or disadvantage. Natural selection does not affect the frequency of neutral mutations. |
| Balancing selection | Occurs when natural selection maintains stable frequencies of multiple alleles in the gene pool of a population. |
| Heterozygote advantage | Occurs when an organism with two different alleles of a particular gene (heterozygote) has greater fitness that an organism with two identical copies of either allele (homozygote). |
| Frequency-dependent selection | The fitness of a phenotype is proportional to its frequency in the population. |
| Negative frequency-dependent selection | The fitness of a phenotype declines if it becomes too abundant in the population. |
| Microevolution | Evolution at the population level. changes in allele frequency, occurs mainly through natural selection or genetic drift, can occur quickly (over generations). |
| Macroevolution | Broad patterns of evolutionary changes above the species level, occurs on geological time scales. |
| Biological Species Concept (BSC) | A species is a group of actually interbreeding individuals that produce viable, fertile offspring, and are reproductively isolated from other species. CANNOT be applied to fossils and asexual organisms. |
| Morphological Species Concept | Defines a species by structural features, it applies to sexual and asexual species but relies on subjective criteria. |
| Ecological Species Concept | Defines a species as a set of organisms adapted to a particular set of resources, called a niche, in the environment. Views a species in terms of its ecological niche and applies to sexual and asexual species. |
| Phylogenetic Species Concept | Defines a species as the smallest group of individuals on a phylogenetic tree. |
| Reproductive Isolation | Caused by biological factors that impede two species from interbreeding and producing viable, fertile offspring (hybrids). |
| Hybrids | Offspring of crosses between different species. |
| Definition of Life | Any living being must have organization, metabolism, response to stimuli, homeostasis, adaptation, and reproduction. |
| Geologic Record | Divided into the Archaean, the Proterozoic, and the Phanerozoic eons. The Phanerozoic eon includes the last half billion years and encompasses multicellular eukaryotic life. |
| Fossil Record | Provides direct evidence of evolutionary history, however it is biased and incomplete. |
| Fossilization | Requires burial in sediment, but sediment accumulates episodically and discontinuously, and fossils typically preserve only hard parts of the organisms. |
| Replacement Fossils | Have had their tissues replaced by minerals |
| Trace Fossils | record evidence of behaviour (tracks, burrows, feces) |
| Preserved Fossils | Retain their original organic material (carbon films, amber, tar or peat, frozen) |
| Relative Dating | Sedimentary strata reveal the relative ages of fossils. |
| Absolute (Radiometric) Dating | Radioactive decay of isotopes of various elements provides a means of determining the age of fossils or rocks. |
| Plate Tectonics Theory | Considers that the Earth's crust is composed of large plates that have been slowly moving since about 3.4 billion years ago. |
| Permian Extinction | Defines the boundary between the Paleozoic and Mesozoic eras 252 million years ago. Earth's most severe mass extinction event. |
| Cretaceous Extinction |
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ldquinn
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