Unit 5: Evolution and Biodiversity Flashcards
Define evolution
Evolution is the cumulative changes in heritable characteristics of a population.
Where are evolutionary changes present?
Evolutionary changes are present in the population’s gene pool as changes in allele frequency.
What is the basis for evolution?
The basis for evolution is genetics and how the environment interacts with heritable characteristics
Who first publicised the process for the basis of evolution being natural selection and when?
The basis for all evolution is natural selection which is a process first publicised in the 19th century by Charles Darwin and Alfred Wallace
What does the process of natural selection explain?
The process of natural selection explains how a species evolves and survives as a consequence of its ability to adapt, which depends on its genetic variability and whether the variability is an advantage to the species.
What are the factors that can contribute to changing environments?
The factors that can contribute to changing environments include climate change, natural disasters, immigration of a new predator/prey, emigration of a predator/prey, or arrival of a new competitor.
What happens to organisms that survive hostile or changing circumstances?
Organisms that survive hostile or changing circumstances usually live to reproductive age and pass on their genes to their progeny (offspring).
When does evolution occur?
Evolution occurs when the heritable characteristics of a species change over time.
What does the fossil record do?
The fossil record provides a record of the order of physical changes in a species over time, and may also provide evidence of behavioural changes. The fossil record provides evidence for the evolution and succession of the complexity of traits. For example, it shows prokaryotic cells precede eukaryotic cells and that invertebrate animals precede vertebrates.
What are some forms of fossils that show structural changes?
Fossils that show structural changes may come in forms such as molds, imprints, casts, and possibly preserved organisms or parts of organisms.
What are trace fossils?
Trace fossils give an indication of behavioural changes of an organism. These may include footprints, feces, or burrows.
Where do fossils typically form?
Fossils typically form in sedimentary rock such as limestone and shale.
What are layers/strata?
Layers and strata are formed by sedimentary rocks. Dead organisms can be trapped in these layers and while the softer tissues decompose, organic materials such as bone or shells can form different types of fossils, which are slowly buried and pressed into the Earth.
How do we know how old a fossil is?
When examining sedimentary rock strata, older fossils are typically buried deeper in the Earth than newer fossils which help scientists place them in chronological order.
Why is the fossil record incomplete?
The fossil record is incomplete because only hard parts of organisms can be preserved and normally only fragments remain. We also don’t have evidence of change in every generation since there’s many missing links but we have records of very important ones.
What are transitional fossils?
Transitional fossils show records of important links that show evolutionary transitions. They display common characteristics between ancestral groups and show evidence for macroevolution
Which important transitional fossil was found in 1860?
An important transitional fossil first found in 1860 was of the archaeopteryx. This fossil shows the transition of birds from prehistoric reptiles.
Define heritable characteristics
Heritable characteristics are the characteristics that an organism possesses due to its genetic make-up. These can be inherited by the organism’s offspring.
What are heritable characteristics in the form of?
Heritable characteristics are in the form of alleles on chromosomes.
Define macroevolution
Macroevolution occurs on a large scale and leads to the development of new species.
What did radioisotopes do?
In the 20th century, radioisotopes allowed more accurate dating methods to become available, supporting the chronology of fossils. This technique was known as radioisotope dating.
When does natural selection occur?
Natural selection occurs when people have genetic variations.
What is selective breeding?
Selective breeding(also known as artificial selection) is a form of artificial selection in which organisms with certain characteristics are chosen by humans because they’re of some benefit. These organisms are bred to produce offspring that have the same genes, and therefore the same characteristics. This happens only through human intervention
What is natural selection?
Natural selection happens when species have variation and certain traits are selected because they help the species reach a reproductive age and pass on their genes
Why do humans do selective breeding?
Humans use selective breeding to try (through genetic crosses) to make a breed that has desired characteristics.
How was selective breeding used on wolves?
The original bloodline of household dogs is from wolf-like animals. It’s thought that docile wolves were accepted around human campsites because they were able to feed on leftover food scraps. The wolves that were able to eat could live longer and pass the docile gene to their offspring. This is natural selection. Once humans realised these animals could be of use they started breeding them for these docile traits so they could be tamed and trained and this evolved into the domestic dog. Today’s domestic dog (Canis lupus familiaris or Canis familiaris) is a subspecies of the gray wolf (Canis lupus)
What is a breed?
Abreedis a group of animals within a species that have specific and similar characteristics.
What are some examples of selective breeding?
Examples of selective breeding:
- Breeding egg-laying hens to lay lots of eggs
- Breeding race horses for speed
- Breeding dogs for herding, hunting or simply for specific physical features
- Breeding cattle for increased meat or milk production
- Breeding of crops to be disease- or cold-weather-resistant in order to increase production
- Breeding of plants to produce larger and sweeter fruits.
What is microevolution?
Microevolution occurs on a small scale within a species. For example, certain alleles becoming more dominant in following generations.
What does homologous mean in biology?
In biology, homologous refers to something similar in position, structure, and evolutionary origin but not necessarily function.
What is the relation between a human arm and a dolphin flipper?
A arm is said to be homologous to the flipper of a dolphin, it means these structures share the same origin and ancestral form. Despite having different appearances and functions, the human arm and dolphin flipper share a similar arrangement of bones in each structure. The five digits (phalanges) suggest they had a common ancestor, but the species diverged to be better adapted to their individual environments.
Draw a pentadactyl limb
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What structure do humans, dolphins, mammals, birds, amphibians, and reptiles share and what is it an example of?
Humans, dolphins, mammals, birds, amphibians, and reptiles share a structure called a pentadactyl limb. A pentadactyl limb is a good example of divergent evolution, which is when there’s an accumulation of differences between different groups that lead to the formation of a new species, showing macroevolution.
How does divergent evolution occur?
Divergent evolution occurs from adaptive radiation, which is a form of microevolution within a species that uses the same structure for different functions due to varying niches.
What is a pentadactyl limb?
A pentadactyl limb is a limb with 5 digits found in amphibians, reptiles, birds, and mammals.
What is divergent evolution?
Divergent evolution is when two separate species evolve from the same ancestor, but become different species that can no longer interbreed. This can be seen through species having similar structures that they use in different ways because of their environment.
Define adaptive radiation
Adaptive radiation is a process in which organisms rapidly diverge from the original species into several new forms specialised to make use of different environmental niches. This can lead to divergent evolution and the development of a new species. This explains homologous structures. Species experiencing adaptive radiation may be geographically isolated.
What is an analogous structure?
Analogous means to perform a similar function but have different evolutionary origin. An analogous structure is the opposite of a homologous structure. In an analogous structure, the function may be similar but there’s no similarity in the bone structure or a common ancestor.
What is convergent evolution?
Convergent evolution is when organisms that aren’t closely related evolve similar structures for similar structures, often because their habitats or diets are similar.
Define speciation
Speciation is the process by which new species form.
How many species are present on earth?
It is estimated the number of species on earth range from 10 to 50 million, but only about 1.5 million have been catalogued so far.
What are discontinuous variations?
Discontinuous variations are a type of variation influenced by a gene or a few genes, can be put into categories, and is not influenced by the environment. An example is the human blood type.
What are continuous variations?
A continuous variation is a variation controlled by many genes, has a wide range of variability, and is easily influenced by the environment. Continuous variations are more common than discontinuous variations. An example are height, as it has many different variations.
How do species form?
When two species become genetically different enough that they can’t interbreed to make fertile offspring anymore, then speciation has occurred. A possibility is that one species evolves overtime until it’s genetically different enough from the original species that it’s considered a new species. Just one species evolving and becoming only one new species is rare. More often, one species branches to become various different species.
What are reasons populations might branch off?
Physical separation of populations is one reason why branching of speciation may occur.
Define speciation
Speciation is the process by which new species form
What is an example of how a change in the environment can make an evolutionary adaptation occur?
A good example of how a change in the environment can precipitate an evolutionary adaptation is seen in the peppered moth, Biston betularia. The peppered moth is active at night and roosts during the day. It rests on trees and uses tree bark covered with lichen as camouflage so birds will not prey on it.
What are the two main morphs/variations of Biston betularia?
Populations ofBiston betulariaconsist of two main morphs, or variations: a darker and a lighter coloured moth. The darker allele is dominant over the lighter allele, and the darker codes for the moth to make more melanin. The darker variety (the melanistic morph) was better camouflaged in highly industrial areas in the UK where large quantities of soot (caused by pollution) resulted in darker tree bark. The lighter colour was better adopted to non-polluted areas, and was more frequent there as well.
What is industrial melanism?
Industrial melanism is the change in the melanin-producing allele frequency from light to dark due to environmental changes brought on by industry pollution.
What is transient polymorphism?
Transient polymorphism is the gradual change in the allele frequency of a population due to the slow replacement of one gene of another.
What is balanced polymorphism?
Balanced polymorphism is a balance between both forms of the allele variations within a population
What is the goal of evolution?
The goal of evolution is for species to be able to survive, not to get better.
What are the 6 pieces of evidence for evolution?
- Fossil evidence
- Biogeography
- Comparitive anatomy
- Selective breeding
- Embryology
- Molecular evidence
What is a struggle of using fossil evidence?
A struggle of using fossil evidence is that it makes it difficult to find transitional fossils since only a small portion of organisms become fossils
Define relative dating
Relative dating describes that older organisms are found lower in stata
Define radiometric dating
Radiometric dating defines how radioactive isotopes decay at a constant rate. The the rate of decay is known as the half life.
Define a transitional fossil
A transitional Fossil is any fossil that exhibits traits common to both an ancestral group and its derived descendant group.
Define biogeography
Biogeography is the study of the geographical distribution of species. Close locations have more similar species compared to geographically distant locations with the same type of organisms.
What is comparative anatomy?
Comparative anatomy looks at the similarities and differences in organism anatomy. Species with similar anatomical features may share a common ancestor.
What 3 structures does comparative anatomy look at?
Comparative anatomy looks at homologous, analogous, and vestigial structures.
Define homologous structures
Homologous structures are parts in different organisms that have the same structure but different function. They are a product of divergent evolution.
Define analogous structures
Analogous structures are parts in different organisms with similar functions but different anatomies, and don’t showcase any recent common ancestry.. They are a result of convergent evolution.
