Chapter 21: The Evidence for Evolution

65 vocabulary flashcards generated from lecture notes on 'The Evidence for Evolution,' covering topics such as Darwin's finches, artificial selection, fossil evidence, anatomical evidence (homologous, vestigial structures, embryonic similarities), biogeography, and convergent evolution.

Galapagos Islands

Location where Darwin collected finch specimens in 1835, which later provided evidence for natural selection.

John Gould

Ornithologist who confirmed the identity of Darwin's finch specimens from the Galapagos Islands.

Galapagos Finches

Species of finches showing differences in beaks and feeding habits, which diversified from an ancestral finch.

Ancestral finch

The original finch species that colonized the Galapagos Islands and diversified into various new species adapted to different habitats.

Warbler finch

A species of Galapagos finch whose beak shape closely resembles that of warblers, despite not being closely related to them.

31 specimens

The number of finch specimens Darwin collected from 3 islands in the Galapagos in 1835.

14 species (finches)

The number of finch species now recognized on the Galapagos Islands, evolved from a single ancestral form.

Seed eaters (finches)

Galapagos finches characterized by powerful beaks adapted for crushing seeds.

Fruit and bud eaters (finches)

Galapagos finches characterized by smaller and narrower beaks, adapted for consuming fruit and buds.

Sharp-beaked ground finch

A subspecies of finch that normally eats seeds and insects, but occasionally supplements its diet by drinking blood from seabirds.

Blue-footed boobies

Seabirds from which the sharp-beaked ground finch occasionally drinks blood to supplement its diet.

Woodpecker finch

A Galapagos finch known for using tools like twigs or cactus spines to pry out grubs from dead branches.

Darwin's selection hypothesis

The idea that differences among finch species in beak size and shape evolved as the species adapted to use different food resources.

Artificial selection

Change in the genetic structure of populations resulting from selective breeding by humans.

Selective breeding

The process by which humans favor individuals with certain phenotypic traits, allowing them to reproduce and pass on their genes to the next generation.

Phenotypic traits

Observable characteristics of an organism that are targeted and selected for in selective breeding.

Evolutionary change (artificial selection)

Substantial alterations in the genetic makeup of populations that result from human-imposed selective breeding.

Fruit flies (Drosophila)

Organisms frequently used in laboratory experiments to demonstrate that selection can produce rapid evolutionary change.

Directional selection

A type of selection that favors individuals at one extreme of a phenotypic range, leading to a shift in the mean value of the population.

Mutation and recombination

Biological processes that continuously introduce new variation into populations, allowing selection to move a population beyond its original range.

Modified crops and livestock

Familiar agricultural plants and animals that are radically different from their wild ancestors due to generations of human selection.

Agricultural selection

The process of human selection for desirable traits in crops and livestock over many generations, leading to extensive modification.

Oil content of corn kernels

A specific trait in corn that scientists experimentally selected for, increasing its average percentage significantly over generations.

Two largest oil content (20%)

The top percentage of individuals (20%) selected to reproduce in an experiment targeting increased oil content in corn kernels.

19.4% (oil content)

The average oil content reached in corn kernels after 90 generations of artificial selection, starting from 4.5%.

Domesticated breeds

Varieties of animals (e.g., dogs, cats, pigeons) produced by human-imposed selection for particular purposes or aesthetic values.

Greyhound dogs

A specific dog breed developed through selection for maximal running ability, characterized by long legs, great muscle mass, and an arched back.

Dachshund dogs

A specific dog breed developed through selection for dogs capable of entering narrow holes in pursuit of badgers.

Esthetic value

The reason why some domesticated varieties, such as certain cat breeds, are selected, focusing on appearance rather than utility.

Fossil record

The most direct evidence of evolution, consisting of the preserved remains of once-living organisms.

Fossils

Preserved remains of once-living organisms, found in various forms including amber, permafrost, dry caves, and rock formations.

Fossilization process

A sequence of three events required for rock fossils to form: organism burial, mineralization of hard tissue, and hardening of surrounding sediment.

Burial (fossilization)

The initial step in the formation of rock fossils, where an organism is quickly covered by sediment preventing decay.

Rarity of fossilization

A limitation of the fossil record, as most remains decay or are scavenged before the fossilization process can begin.

Inaccessible rocks (fossils)

A limitation of the fossil record, as many fossils occur in rocks located in areas difficult for scientists to reach.

Erosion (fossils)

A natural process that can destroy discovered or exposed fossils, further limiting the fossil record.

Relative dating

A method used in Darwin's day to estimate the age of fossils by their position within rock strata, with lower strata generally being older.

Sedimentary rocks

Rocks formed from layers of sediment, whose relative positions can be used to estimate the age of embedded fossils.

Isotopic dating

A modern, highly accurate method to estimate the age of fossils based on the known decay rates of unstable isotopes within the rock.

Isotopes

Different forms of the same element that have the same number of protons but different numbers of neutrons.

Less stable isotope

An isotope that undergoes radioactive decay over time, transforming into a more stable isotope, a process used in isotopic dating.

Half-life

The known and constant rate at which less stable isotopes decay, used to calculate the age of rocks and fossils.

Evolutionary change (fossils)

The documentation by fossils of successive alterations in life forms over geological time, illustrating the course of life through time.

Origin of prokaryotes

A major event in the history of life, documented by the fossil record, marking the appearance of the earliest and simplest cellular organisms.

Origin of eukaryotes

A major event in the history of life, documented by the fossil record, marking the appearance of cells with a nucleus and other membrane-bound organelles.

Rise of land-dwelling organisms

A significant evolutionary transition documented by fossils, showing how life moved from aquatic environments to terrestrial ones.

Reign of the dinosaurs

A geological era extensively documented by the fossil record, characterized by the dominance of various dinosaur species.

Origin of humans

A more recent event in evolutionary history, supported by detailed fossil evidence of ancestral hominins.

Biodiversity waxing and waning

The pattern shown in the fossil record where the variety of life forms has increased and decreased over geological time, often due to mass extinctions and subsequent radiations.

Intermediate forms

Fossils that show transitional features between different major groups of organisms, illustrating how evolution occurred over time.

Archaeopteryx

The oldest known bird, living approximately 165 million years ago, famous for its remarkable preservation and intermediate features.

Birds and dinosaurs (Archaeopteryx)

The two groups that Archaeopteryx is considered an evolutionary intermediate between, showcasing traits from both.

Dinosaur traits (Archaeopteryx)

Features observed in Archaeopteryx such as teeth, a long bony tail, and claws on its wings, linking it to dinosaurs.

Feathers and modern bird traits (Archaeopteryx)

Features observed in Archaeopteryx such as well-developed feathers and a wishbone, linking it to modern birds.

Fossil record gaps (filled)

Despite initial incompleteness, paleontologists have continuously discovered new fossils that help to fill in missing links, connecting major groups of vertebrates.

Homologous structures

Structures in different species that have different appearances and functions but are derived from the same body part in a common ancestor.

Vertebrate forelimb bones

An example of homologous structures, where the same underlying bone pattern is found in the arms, wings, or flippers of different vertebrates, adapted for various uses.

Embryonic development similarities

Similarities observed early in the development of embryos of different vertebrate species, suggesting a common ancestry.

Pharyngeal gill pouches

Structures present in all vertebrate embryos during early development, which later differentiate into different structures in various species.

Glands and ducts (humans)

The structures that pharyngeal gill pouches develop into in humans (e.g., Eustachian tubes, tonsils, thymus, parathyroid glands).

Gill slits (fishes)

The structures that pharyngeal gill pouches develop into in fishes, enabling respiration.

Tail (vertebrate embryos)

A structure present in early vertebrate embryos, which is later lost in certain groups such as apes and humans.

Imperfectly suited structures

Features of organisms that illustrate how natural selection must work with available variation, not always leading to perfectly optimal designs.

Neck vertebrae

An example of a structure that can be imperfectly suited, as seen in the fixed number of vertebrae in mammals despite varied neck lengths.

Plesiosaurs

Extinct marine reptiles known for having unusually long necks, with some species possessing as many as 76 neck vertebrae, demonstrating a high degree of flexibility.

Giraffes

Mammals that possess only 7 very long neck vertebrae, the same number as other mammals, illustrating constraints on evolutionary adaptation.

Elongation of bones

A more likely path for increasing neck length in giraffes than developing additional vertebral bones, demonstrating how existing structures are modified.

Vestigial structures

Morphological features that have no apparent current function and are thought to be evolutionary relics, resembling structures present in their ancestors.

Boas and pythons

Snakes that possess hip bones and rudimentary hindlimbs, which are examples of vestigial structures.

Claws (manatees)

Small, non-functional structures found on the flippers of manatees, considered vestigial remnants of ancestral limbs.

Coccyx ("tailbone")

A vestigial structure in humans, representing the remnants of a tail found in ancestral primates.

Appendix

A small, finger-shaped organ projecting from the large intestine in humans, considered a vestigial structure with no clear modern function.

Wisdom teeth

The third molars in humans, often problematic and extracted, considered vestigial due to changes in diet and jaw size.

Pseudogenes

Traces of previously functioning genes that have become inactive due to mutations, considered molecular vestigial structures.

Biogeography

The study of the geographic distribution of species, which provides evidence for evolution through patterns of species presence and absence.

Convergent evolution

The process by which different geographical areas exhibit groups of distantly related organisms that have strikingly similar appearances due to similar selective pressures in similar environments.

Marsupials

A major group of mammals characterized by their young being born very premature and developing further, often in a pouch, while latched onto the mother's nipple.

Placental mammals

A major group of mammals characterized by their young developing extensively within the mother's uterus until born at a more advanced stage of maturity and independence.

Constant source of nutrients

The benefit provided to marsupial young while developing in the pouch, allowing continuous growth with the mother's milk.

Maturity and independence

The varying degrees to which placental mammal young are born, enabling them to survive in the external environment.

50 million years ago

The approximate time when Australia separated from other continents, leading to independent evolution of its flora and fauna.

Rodents (placental)

One of the few types of placental mammals that colonized Australia relatively recently, about 5 million years ago.

Similar forms

The striking resemblances between Australian marsupials and placental mammals on other continents, suggesting that similar selective pressures led to convergent evolution.

Convergent evolution widespread

The phenomenon indicating that when species interact with the environment in similar ways, they often develop the same evolutionary adaptations.

Streamlined body form

An adaptation for fast movement through water, which has evolved numerous times independently (convergent evolution) in aquatic animals to reduce friction.

Lactase

The enzyme responsible for digesting milk sugar (lactose).

Lactose intolerance

A condition resulting from the cessation of lactase production in most human populations after childhood, making dairy digestion difficult.

Lactase persistence

The ability of certain human populations (e.g., African and European cattle-raising groups) to produce lactase throughout their lives, an adaptation driven by convergent evolution.

Different mutations

The underlying genetic cause of lactase persistence in African and European populations, demonstrating that this adaptation arose independently (convergently) in different groups.