A report on Species

All adult Eurasian blue tits share the same coloration, unmistakably identifying the morphospecies.
A region of the gene for the cytochrome c oxidase enzyme is used to distinguish species in the Barcode of Life Data Systems database.
The cladistic or phylogenetic species concept is that a species is the smallest lineage which is distinguished by a unique set of either genetic or morphological traits. No claim is made about reproductive isolation, making the concept useful also in palaeontology where only fossil evidence is available.
A chronospecies is defined in a single lineage (solid line) whose morphology changes with time. At some point, palaeontologists judge that enough change has occurred that two species (A and B), separated in time and anatomy, once existed.
A cougar, mountain lion, panther, or puma, among other common names: its scientific name is Puma concolor.
The type specimen (holotype) of Lacerta plica, described by Linnaeus in 1758
Ernst Mayr proposed the widely used Biological Species Concept of reproductive isolation in 1942.
Palaeontologists are limited to morphological evidence when deciding whether fossil life-forms like these Inoceramus bivalves formed a separate species.
Horizontal gene transfers between widely separated species complicate the phylogeny of bacteria.
John Ray believed that species breed true and do not change, even though variations exist.
Carl Linnaeus created the binomial system for naming species.
Blackberries belong to any of hundreds of microspecies of the Rubus fruticosus species aggregate.
The butterfly genus Heliconius contains many similar species.
The Hypsiboas calcaratus–fasciatus species complex contains at least six species of treefrog.
Carrion crow
Hybrid with dark belly, dark gray nape
Hybrid with dark belly
Hooded crow
Seven "species" of Larus gulls interbreed in a ring around the Arctic.
Opposite ends of the ring: a herring gull (Larus argentatus) (front) and a lesser black-backed gull (Larus fuscus) in Norway
A greenish warbler, Phylloscopus trochiloides
Presumed evolution of five "species" of greenish warblers around the Himalayas

Basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.

- Species
All adult Eurasian blue tits share the same coloration, unmistakably identifying the morphospecies.

80 related topics with Alpha

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Lucretius

Evolution

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Change in the heritable characteristics of biological populations over successive generations.

Change in the heritable characteristics of biological populations over successive generations.

Lucretius
Alfred Russel Wallace
Thomas Robert Malthus
In 1842, Charles Darwin penned his first sketch of On the Origin of Species.
DNA structure. Bases are in the centre, surrounded by phosphate–sugar chains in a double helix.
Duplication of part of a chromosome
This diagram illustrates the twofold cost of sex. If each individual were to contribute to the same number of offspring (two), (a) the sexual population remains the same size each generation, where the (b) Asexual reproduction population doubles in size each generation.
Mutation followed by natural selection results in a population with darker colouration.
Simulation of genetic drift of 20 unlinked alleles in populations of 10 (top) and 100 (bottom). Drift to fixation is more rapid in the smaller population.
Homologous bones in the limbs of tetrapods. The bones of these animals have the same basic structure, but have been adapted for specific uses.
A baleen whale skeleton. Letters a and b label flipper bones, which were adapted from front leg bones, while c indicates vestigial leg bones, both suggesting an adaptation from land to sea.
Common garter snake (Thamnophis sirtalis sirtalis) has evolved resistance to the defensive substance tetrodotoxin in its amphibian prey.
The four geographic modes of speciation
Geographical isolation of finches on the Galápagos Islands produced over a dozen new species.
Tyrannosaurus rex. Non-avian dinosaurs died out in the Cretaceous–Paleogene extinction event at the end of the Cretaceous period.
The hominoids are descendants of a common ancestor.
As evolution became widely accepted in the 1870s, caricatures of Charles Darwin with an ape or monkey body symbolised evolution.

It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms and molecules.

Description of rare animals (写生珍禽图), by Song dynasty painter Huang Quan (903–965)

Taxonomy (biology)

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Scientific study of naming, defining and classifying groups of biological organisms based on shared characteristics.

Scientific study of naming, defining and classifying groups of biological organisms based on shared characteristics.

Description of rare animals (写生珍禽图), by Song dynasty painter Huang Quan (903–965)
Title page of Systema Naturae, Leiden, 1735
Evolution of the vertebrates at class level, width of spindles indicating number of families. Spindle diagrams are typical for evolutionary taxonomy
The same relationship, expressed as a cladogram typical for cladistics
The basic scheme of modern classification. Many other levels can be used; domain, the highest level within life, is both new and disputed.
Type specimen for Nepenthes smilesii, a tropical pitcher plant
A comparison of phylogenetic and phenetic (character-based) concepts

The principal ranks in modern use are domain, kingdom, phylum (division is sometimes used in botany in place of phylum), class, order, family, genus, and species.

The Tasmanian tiger (Thylacinus cynocephalus) is an example of an extinct species.

Extinction

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The Tasmanian tiger (Thylacinus cynocephalus) is an example of an extinct species.
External mold of the extinct Lepidodendron from the Upper Carboniferous of Ohio
Skeleton of various extinct dinosaurs; some other dinosaur lineages still flourish in the form of birds
The dodo of Mauritius, shown here in a 1626 illustration by Roelant Savery, is an often-cited example of modern extinction.
The passenger pigeon, one of the hundreds of species of extinct birds, was hunted to extinction over the course of a few decades.
Scorched land resulting from slash-and-burn agriculture
The golden toad was last seen on May 15, 1989. Decline in amphibian populations is ongoing worldwide.
The large Haast's eagle and moa from New Zealand
Tyrannosaurus, one of the many extinct dinosaur genera. The cause of the Cretaceous–Paleogene extinction event is a subject of much debate amongst researchers.
Georges Cuvier compared fossil mammoth jaws to those of living elephants, concluding that they were distinct from any known living species.
A great hammerhead caught by a sport fisherman. Human exploitation now threatens the survival of this species. Overfishing is the primary driver of shark population declines, which have fallen over 71% since 1970.

Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species.

Diagram of a fly from Robert Hooke's innovative Micrographia, 1665

Biology

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Scientific study of life.

Scientific study of life.

Diagram of a fly from Robert Hooke's innovative Micrographia, 1665
In 1842, Charles Darwin penned his first sketch of On the Origin of Species.
In the Bohr model of an atom, electrons (blue dot) orbit around an atomic nucleus (red-filled circle) in specific atomic orbitals (grey empty circles).
Model of hydrogen bonds (1) between molecules of water
Organic compounds such as glucose are vital to organisms.
A phospholipid bilayer consists of two adjacent sheets of phospholipids, with the hydrophilic tails facing inwards and the hydrophobic heads facing outwards.
The (a) primary, (b) secondary, (c) tertiary, and (d) quaternary structures of a hemoglobin protein
Structure of an animal cell depicting various organelles
Structure of a plant cell
Example of an enzyme-catalysed exothermic reaction
Respiration in a eukaryotic cell
Photosynthesis changes sunlight into chemical energy, splits water to liberate O2, and fixes CO2 into sugar.
In meiosis, the chromosomes duplicate and the homologous chromosomes exchange genetic information during meiosis I. The daughter cells divide again in meiosis II to form haploid gametes.
Punnett square depicting a cross between two pea plants heterozygous for purple (B) and white (b) blossoms
Bases lie between two spiraling DNA strands.
The extended central dogma of molecular biology includes all the processes involved in the flow of genetic information.
Regulation of various stages of gene expression
Composition of the human genome
Construction of recombinant DNA, in which a foreign DNA fragment is inserted into a plasmid vector
Model of concentration gradient building up; fine yellow-orange outlines are cell boundaries.
Natural selection for darker traits
Comparison of allopatric, peripatric, parapatric and sympatric speciation
Bacteria – Gemmatimonas aurantiaca (-=1 Micrometer)
Archaea – Halobacteria
Diversity of protists
Diversity of plants
Diversity of fungi. Clockwise from top left: Amanita muscaria, a basidiomycete; Sarcoscypha coccinea, an ascomycete; bread covered in mold; chytrid; Aspergillus conidiophore.
Bacteriophages attached to a bacterial cell wall
Root and shoot systems in a eudicot
The xylem (blue) transports water and minerals from the roots upwards whereas the phloem (orange) transports carbohydrates between organs.
Reproduction and development in sporophytes
Negative feedback is necessary for maintaining homeostasis such as keeping body temperature constant.
Diffusion of water and ions in and out of a freshwater fish
Different digestive systems in marine fishes
Respiratory system in a bird
Circulatory systems in arthropods, fish, reptiles, and birds/mammals
Asynchronous muscles power flight in most insects. a: Wings b: Wing joint c: Dorsoventral muscles power upstrokes d: Dorsolongitudinal muscles power downstrokes.
Mouse pyramidal neurons (green) and GABAergic neurons (red)
Sexual reproduction in dragonflies
Cleavage in zebrafish embryo
Processes in the primary immune response
Brood parasites, such as the cuckoo, provide a supernormal stimulus to the parenting species.
Terrestrial biomes are shaped by temperature and precipitation.
Reaching carrying capacity through a logistic growth curve
A (a) trophic pyramid and a (b) simplified food web. The trophic pyramid represents the biomass at each level.
Fast carbon cycle showing the movement of carbon between land, atmosphere, and oceans in billions of tons per year. Yellow numbers are natural fluxes, red are human contributions, white are stored carbon. Effects of the slow carbon cycle, such as volcanic and tectonic activity, are not included.
Efforts are made to preserve the natural characteristics of Hopetoun Falls, Australia, without affecting visitors' access.

A species is a group of organisms that mate with one another and speciation is the process by which one lineage splits into two lineages as a result of having evolved independently from each other.

Estimated accepted genus totals by kingdom - based on Rees et al., 2020

Genus

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Taxonomic rank used in the biological classification of living and fossil organisms as well as viruses.

Taxonomic rank used in the biological classification of living and fossil organisms as well as viruses.

Estimated accepted genus totals by kingdom - based on Rees et al., 2020
Number of reptile genera with a given number of species. Most genera have only one or a few species but a few may have hundreds. Based on data from the Reptile Database (as of May 2015).

In the hierarchy of biological classification, genus comes above species and below family.

The title page of the 1859 edition
of On the Origin of Species

On the Origin of Species

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Work of scientific literature by Charles Darwin that is considered to be the foundation of evolutionary biology.

Work of scientific literature by Charles Darwin that is considered to be the foundation of evolutionary biology.

The title page of the 1859 edition
of On the Origin of Species
Darwin pictured shortly before publication
Cuvier's 1799 paper on living and fossil elephants helped establish the reality of extinction.
In mid-July 1837 Darwin started his "B" notebook on Transmutation of Species, and on page 36 wrote "I think" above his first evolutionary tree.
Darwin researched how the skulls of different pigeon breeds varied, as shown in his Variation of Plants and Animals Under Domestication of 1868.
A photograph of Alfred Russel Wallace (1823–1913) taken in Singapore in 1862
On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, 2nd edition. By Charles Darwin, John Murray, London, 1860. National Museum of Scotland
American botanist Asa Gray (1810–1888)
John Gould's illustration of Darwin's rhea was published in 1841. The existence of two rhea species with overlapping ranges influenced Darwin.
This tree diagram, used to show the divergence of species, is the only illustration in the Origin of Species.
In the 1870s, British caricatures of Darwin with a non-human ape body contributed to the identification of evolutionism with Darwinism.
Huxley used illustrations to show that humans and apes had the same basic skeletal structure.
Haeckel showed a main trunk leading to mankind with minor branches to various animals, unlike Darwin's branching evolutionary tree.
The liberal theologian Baden Powell defended evolutionary ideas by arguing that the introduction of new species should be considered a natural rather than a miraculous process.
A modern phylogenetic tree based on genome analysis shows the three-domain system.

Every species is fertile enough that if all offspring survived to reproduce, the population would grow (fact).

A sampling of fungi collected during summer 2008 in Northern Saskatchewan mixed woods, near LaRonge, is an example regarding the species diversity of fungus. In this photo, there are also leaf lichens and mosses.

Biodiversity

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Variety and variability of life on Earth.

Variety and variability of life on Earth.

A sampling of fungi collected during summer 2008 in Northern Saskatchewan mixed woods, near LaRonge, is an example regarding the species diversity of fungus. In this photo, there are also leaf lichens and mosses.
Distribution of living terrestrial vertebrate species, highest concentration of diversity shown in red in equatorial regions, declining polewards (towards the blue end of the spectrum) (Mannion 2014)
Apparent marine fossil diversity during the Phanerozoic
Summer field in Belgium (Hamois). The blue flowers are Centaurea cyanus and the red are Papaver rhoeas.
Amazon Rainforest in South America
The diverse forest canopy on Barro Colorado Island, Panama, yielded this display of different fruit
Agriculture production, pictured is a tractor and a chaser bin
Eagle Creek, Oregon hiking
Discovered and predicted total number of species on land and in the oceans
The Forest Landscape Integrity Index measures global anthropogenic modification on remaining forests annually. 0 = Most modification; 10= Least.
Deforestation and increased road-building in the Amazon Rainforest in Bolivia cause significant concern because of increased human encroachment upon wild areas, increased resource extraction and further threats to biodiversity.
Male Lophura nycthemera (silver pheasant), a native of East Asia that has been introduced into parts of Europe for ornamental reasons
The Yecoro wheat (right) cultivar is sensitive to salinity, plants resulting from a hybrid cross with cultivar W4910 (left) show greater tolerance to high salinity
Polar bears on the sea ice of the Arctic Ocean, near the North Pole. Climate change has started affecting bear populations.
Summary of major biodiversity-related environmental-change categories expressed as a percentage of human-driven change (in red) relative to baseline (blue)
A schematic image illustrating the relationship between biodiversity, ecosystem services, human well-being and poverty. The illustration shows where conservation action, strategies, and plans can influence the drivers of the current biodiversity crisis at local, regional, to global scales.
The retreat of Aletsch Glacier in the Swiss Alps (situation in 1979, 1991 and 2002), due to global warming.
Percentage of forest in legally protected areas, 2020, from the Food and Agriculture Organization publication The State of the World's Forests 2020. Forests, biodiversity and people – In brief
A great deal of work is occurring to preserve the natural characteristics of Hopetoun Falls, Australia while continuing to allow visitor access.

Biodiversity is a measure of variation at the genetic (genetic variability), species (species diversity), and ecosystem (ecosystem diversity) level.

African pygmy kingfisher, showing coloration shared by all adults of that species to a high degree of fidelity.

Speciation

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African pygmy kingfisher, showing coloration shared by all adults of that species to a high degree of fidelity.
Comparison of allopatric, peripatric, parapatric and sympatric speciation
Cichlids such as Haplochromis nyererei diversified by sympatric speciation in the Rift Valley lakes.
Rhagoletis pomonella, the hawthorn fly, appears to be in the process of sympatric speciation.
Reinforcement assists speciation by selecting against hybrids.
Gaur (Indian bison) can interbreed with domestic cattle.
Male Drosophila pseudoobscura
Speciation via polyploidy: A diploid cell undergoes failed meiosis, producing diploid gametes, which self-fertilize to produce a tetraploid zygote. In plants, this can effectively be a new species, reproductively isolated from its parents, and able to reproduce.
Phyletic gradualism, above, consists of relatively slow change over geological time. Punctuated equilibrium, bottom, consists of morphological stability and rare, relatively rapid bursts of evolutionary change.

Speciation is the evolutionary process by which populations evolve to become distinct species.

The bacterium Escherichia coli (E. coli), is a single-celled prokaryote

Organism

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Organism is any organic, living system that functions as an individual entity.

Organism is any organic, living system that functions as an individual entity.

The bacterium Escherichia coli (E. coli), is a single-celled prokaryote
An amoeba is a single-celled eukaryote
Polypore fungi and angiosperm trees are large multicellular eukaryotes.
Precambrian stromatolites in the Siyeh Formation, Glacier National Park. In 2002, a paper in the scientific journal Nature suggested that these 3.5 Gya (billion years old) geological formations contain fossilized cyanobacteria microbes. This suggests they are evidence of one of the earliest known life forms on Earth.
LUCA may have used the Wood–Ljungdahl or reductive acetyl–CoA pathway to fix carbon.

Estimates on the number of Earth's current species range from 2 million to 1 trillion, of which over 1.7 million have been documented.

A red tulip exhibiting a partially yellow petal due to a mutation in its genes

Mutation

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Alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA.

Alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA.

A red tulip exhibiting a partially yellow petal due to a mutation in its genes
Mutation with double bloom in the Langheck Nature Reserve near Nittel, Germany
Prodryas persephone, a Late Eocene butterfly
A covalent adduct between the metabolite of benzo[a]pyrene, the major mutagen in tobacco smoke, and DNA
Five types of chromosomal mutations
Selection of disease-causing mutations, in a standard table of the genetic code of amino acids
The structure of a eukaryotic protein-coding gene. A mutation in the protein coding region (red) can result in a change in the amino acid sequence. Mutations in other areas of the gene can have diverse effects. Changes within regulatory sequences (yellow and blue) can effect transcriptional and translational regulation of gene expression.
The distribution of fitness effects (DFE) of mutations in vesicular stomatitis virus. In this experiment, random mutations were introduced into the virus by site-directed mutagenesis, and the fitness of each mutant was compared with the ancestral type. A fitness of zero, less than one, one, more than one, respectively, indicates that mutations are lethal, deleterious, neutral, and advantageous.
A mutation has caused this moss rose plant to produce flowers of different colors. This is a somatic mutation that may also be passed on in the germline.
Dutch botanist Hugo de Vries making a painting of an evening primrose, the plant which had apparently produced new forms by large mutations in his experiments, by Thérèse Schwartze, 1918

A 2007 study on genetic variations between different species of Drosophila suggested that, if a mutation changes a protein produced by a gene, the result is likely to be harmful, with an estimated 70% of amino acid polymorphisms that have damaging effects, and the remainder being either neutral or marginally beneficial.