Sexual selectionSexual selection is a mechanism of evolution in which members of one sexchoose mates of the other sex (intersexual selection) to mate with, and compete with members of the same sex for access to members of the opposite sex (intrasexual selection). These two forms of selection mean that some individuals have greater reproductive success than others within a population, for example because they are more attractive or prefer more attractive partners to produce offspring.
Secondary sex characteristicA secondary sex characteristic (or secondary sexual characteristic) is a physical characteristic of an organism that is related to or derived from its sex, but not directly part of its reproductive system. In humans, these characteristics typically start to appear during puberty—and include enlarged breasts and widened hips of females, facial hair and Adam's apples on males, and pubic hair on both.
SpeciesA species (pl. species) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. It can be defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour, or ecological niche.
Natural selectionMechanism of evolution by differential reproductionMutation and selectionNatural selection is the differential survival and reproduction of individuals due to differences in the relative fitness endowed on them by their own particular complement of observable characteristics. It is a key law or mechanism of evolution which changes the heritable traits characteristic of a population or species over generations.
Biological sexSex is the phenotypic trait of a sexually reproducing organism in producing gametes of one of two different sizes or shapes—male or female gametes. During sexual reproduction, a male and a female gamete fuse to form a zygote, which develops into an offspring that inherits traits from each parent.
PhenotypeIn genetics, the phenotype (from Ancient Greek (phaínō)'to appear, show' and (túpos)'mark, type') is the set of observable characteristics or traits of an organism. The term covers all traits of an organism other than its genome, however transitory: the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological properties whether reversible or irreversible, and all its behavior, such as a peacock's display.
SpiderSpiders (orderAraneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms. Spiders are found worldwide on every continent except Antarctica, and have become established in nearly every land habitat.DioecyDioecy (from Ancient Greek διοικία (dioikía) 'two households'; adj. dioecious) is a characteristic of species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is biparental reproduction. Dioecy has costs, since only the females directly produce offspring.
ReproductionReproduction (or procreation or breeding) is the biological process by which new individual organisms – offspring – are produced from their parent or parents. There are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms. The cloning of an organism is a form of asexual reproduction.
Leopard sealThe leopard seal (Hydrurga leptonyx), also referred to as the sea leopard, is a long and muscular seal native to the Southern Ocean of Antarctica and southern Patagonia. It is the second largest species of seal in the Antarctic (after the southern elephant seal). It is the same length as, but half the weight of, a walrus. Its fur coat is countershaded, being silver on the bottom and dark gray on the top, and is distinctive for its leopard-like pattern of dark spots.
Bird of preyBirds of prey or predatory birds, also known as raptors, are hypercarnivorous species of bird that actively hunt and feed on other vertebrates, mainly mammals, reptiles, and smaller birds. In addition to speed and strength, these predators have keen eyesight for detecting prey from a distance or during flight, strong feet with sharp talons for grasping or killing prey, and powerful, curved beaks for tearing flesh.
Morphology (biology)In biology, morphology is the study of the form and structure of organisms and their specific structural features. This includes aspects of the outward appearance (shape, structure, color, pattern, size), as well as the form and structure of internal parts like bones and organs, i.e., anatomy. This is in contrast to physiology, which deals primarily with function.*As an Amazon Associate I earn from qualifying purchases.