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BIO1022
Week 1 - 4
| Question | Answer |
|---|---|
| Explain the conclusion that Darwin and Wallace came to that helps explain the evolution of species, and describe how it relies on the observations of Malthus. | Alfred Wallace and Charles Darwin happened to be working on the same theory. - Species have evolved over time - Natural selection brings about adaptation - Best adapted would leave more offsprings - Genetic variation |
| Natural Selection | is the process by which evolutionary changes are selected for by nature in a non-random way within a population from one generation to the next. example: Galapagos finches observed on different island. the shape and length of the beaks are dependent on t |
| Sexual Selection | A form of selection that promotes traits that increase an individuals access to reproductive opportunities. example: intrasexual and intersexual. Humans use sexual selection. |
| Artificial Selection | Is the form of directional selections - successfu genotypes are selected by breeder not through competition. example: corn - artificially selected for either high or low oil content. |
| Positive Selection | Increases the frequency of advantages mutation and decrease the frequency of deleterious mutation |
| Negative Selection | Decreases the frequency of a deleterious alleles. |
| Balancing Selection | Acts to maintain 2 or more alleles in a population. Heterozygotes advantage: heterozygote’s fitness is higher than homozygote. example: A and S hemoglobin. A- round red blood cells. S - sickle shaped red blood cell. AA lacks sickle cell anemia but vulner |
| Stabilising Selection | Mainains the status quo and acts against extremes. Keeps a trait the same over time. example: human birth weight. - baby too small: chances of survival after birth too low. - baby too big: hard for mother and baby. SS results in intermediate size babies. |
| Directional Selection | Leads to change in a trait over time. example: galapagos finches |
| Disruptive Selection | Operates in favour of extremes and against intermediate forms. example: apple maggot flies of North America have larvae that originally fed on the fruit of hawthorn trees. After the intro of apples from Europe, these flies have become pests of apple as w |
| Intra-sexual Selection | Competition between members of the same sex (usually males) for access to mates. example: males with large size and horns and other elaborate weaponry are more likely to be selected by females. |
| Inter-sexual Selection | Is a phenomenon where members of one sex (usually females) choose members of the opposite sex example: peacock's tails |
| Biological Species Concept | species are groups of actually/potentially interbreeding populations that are reproductively isolated from other such groups. - not applies to asexual organisms. - hybridisation e.g. elephants in Sri Lanka and India |
| Morphospecies Concept | members of the same species usually species usually look like each other more than other species. example: butterflies |
| Ecological Species Concept | there is one-to-one correspondence between a species and its niche. example: determines whether asexual bacterial lineages are distinct species on the basis of their ecological requirements. |
| Phylogenetic Species Concept | members of a species all share a common ancestry and fate |
| Ring Species | a situation in which two populations which do not interbreed are living in the same region and connected by a geographic ring of populations that can interbreed. |
| Reproductive isolation | the organisms are put into different conditions which causes them to adapt and evolve into new species |
| Pre-zygotic (behaviour) | individuals mate only with individuals based on specific courtship rituals, songs, or other behaviours. |
| Pre-zygotic (gametic) | gametes discharges and interacts with a close related species, gametes - develops incompatibility |
| Pre-zygotic (mechanical incompatibility) | structural configuration of genatalia that prevents mating with another species |
| Pre-zygotic (temporal) | isolate in time. e.g. species flower at different times of the year. no interactions of pollen. |
| Pre-zygotic (geographical/ecological) | isolated in space. e.g. feeding on different plants. |
| Post-zygotic (genetic incompatibility) | genetic dissimilarity between two organisms. e.g. different number of chromosomes sufficient to act as a post-zygotic isolating factor. |
| Allopatric speciation | occurs when a species separates into two separate groups which are isolated from one another |
| Allopatric speciation (dispersal) | when a few members of a species move to a new geographical area |
| Peripatric speciation | is a mode of speciation in which a new species is formed from an isolated peripheral population |
| Allopatric speciation (vicariance) | when a geographic barrier arises, disrupting the gene flow between subpopulations. |
| Allopatric speciation (co-speciation) | A process in which two groups of organisms speciate in response to each other and at the same time, producing matching phylogenies. |
| Sympatric speciation | occurs when there are no physical barriers preventing any members of a species from mating with another, and all members are in close proximity to one another |
| Sympatric speciation (hybridisation) | occurs when two divergent lineages (e.g., species) with independent evolutionary histories come into contact and interbreed |
| convergent evolution | is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. |
| divergent evolution | what occurs when two groups of the same species evolve different traits within those groups in order to accommodate for differing environmental and social pressures. |
| out-group | a taxa or lineage that is outside a group of taxa being studied |
| branch | represent ‘evolutionary distance’ or the amount of ‘change’ over time |
| root | represent an ‘ancestral lineage’, the organisms that evolved to become the common ancestor of all descendants included on our tree. |
| node | splitting point of two branches. Each node represents a common ancestor of all species or groups further along the branch |
| common ancestor | An ancestor shared by two or more descendant species |
| monophyletic group | aka a clade, includes a common ancestor and all descendants of a common ancestor. |
| paraphyletic group | Includes common ancestor and some descendants of that common ancestor |
| polyphyletic group | Does not include a common ancestor |
| homologous characters | characters in different organisms that are similar because they were inherited from a common ancestor that also had that character |
| analogous characters | Structures that are superficially similar but anatomical dissimilar doing the same function |
| synapomorphies | Synapomorphies define monophyletic groups |
| parsimony | Minimum number of changes during evolution |
| Sedimentary rock layers - fossil aging | oldest rocks are at the bottom. the fossils in the older rocks denote that they are relatively older that the rocks in the newer sediments. |
| Radiometric dating - fossil aging | Dating ancient materials using the decay of radioisotopes as a yardstick, including the decay of radioactive 14C to nitrogen for time intervals up to a few tens of thousands of years, and the decay of radioactive uranium to lead for most of Earth history. |
| What effect do mass extinction events have on the evolution of the surviving species, as evidenced by the fossil record? | reduce competition for resources and leave behind many vacant niches |
| anatomical features - primate | - eyes at front of face for better depth - opposable thumb - closely placed nostrils - tail loss |
| anatomical features - ape | - robust canine teeth - earlobes - delayed puberty |
| Which species of extant great ape are humans most related to, and what evidence indicates this? | Species: Chimpanzee ( Pan troglodytes) o Fossil Evidence: |
| evolution | - bipedalism - cranium - foramen magnum - FOXP2 - mandible - sagittal crest |
| multiregional hypothesis | asserts that the Homo erectus, after leaving Africa were divided into different continents in the world where they slowly evolved |
| out-of-Africa hypothesis | believed that humans migrated from Africa to Eurasia replacing all Homo erectus |
| What makes mitochondrial DNA and Y-chromosome DNA ideal for determining the history of human global migration? | variation in the mitochondrial genome (as well as in the Y chromosome in the case of paternal lineages) has been used to delineate how and when humans migrated and occupied the world |
| Which lineages of humans appear to have interbreed with Neanderthals during their migration around the globe? | Neandertals interbred with the ancestors of living Europeans and Asians, who then spread throughout Eurasia. Some of this group of modern humans also encountered Denisovans, picking up the DNA that persists today in Melanesians and some Asians. |
| List the features common to all animals | - multicellular heterotrophic eukaryotes - mostly reproduce sexually |
| Coelom | body cavity |
| Porifera | Commonly known as sponges: sessile animals that range in size from a few mm to a few metres Multicellular |
| Cnidaria | Includes jellyfish, sea anemones and coral Coral: colonial animals, construct large reefs |
| bilateral symmetry | a single plane of symmetry runs from mouth to tail. Bilaterally symmetry animals have a distinct front (anterior) and back (posterior), top (dorsal) and underside (ventral) and right and left |
| bilaterians | bilateral symmetry. the bilaterians are divided into two clades based on their early embryonic development. Deuterostome Gastrulation. Protostome Gastrulation. |
| deuterostomes | the blastopore formed during gastrulation becomes the anus of the organism |
| protostomes | blastopore formed during gastrulation becomes the mouth of the organism |
| ecdysozoa | protosome- nematodes (roundworms) are one of the groups within this clade: Pseudocoelomates have body cavity, bordered by mesoderm and endoderm-derived tissues |
| lophotrochozoa | protosome- Annelids (segmented worms) and Platyhelminthes (flatworms) are two groups within this clade |
| platyhelminthes | Free-living flatworms (marine and terrestrial) as well as internal parasites. They are flat, soft bodies, triploblastic, acoelomate (w/o body cavity) organisms . |
| nematodes | Roundworms are either free-living or parasitic. Soft bodies, triploblastic, pseudocoelomate organisms. Tapered appearance at either end and a tough but flexible cuticle. Very small but some species can grow up to 8 m in length |
| annelids | Segmented or ringed worms. Soft bodies, triploblastic, coelomate organisms and are typical worm-like. |
| molluscs | Diverse phylum containing cephalopods (e.g. squid and Octopus), gastropods (e.g. snails, slugs, nudibranchs) and bivalves (e.g. clams and mussels). they are triploblastic, coelomate organisms with a complex, non-segmented body plan. |
| arthropods | Most diverse of all the phyla in the animal kingdom. Triploblastic, coelomate organisms with complex organ systems. Crustaceans. Insects. Chelicerates. Myriapods. |
| chordate features | - pharyngeal slits - myotomes - post-anal tail - dorsal nerve cord - notochord present only in embryos |
| vertebrates features | - well developed brain and eyes - jaws - cranium - gills - paired fins - vertebrae |
| Describe some of the major evolutionary steps that have allowed vertebrates to expand onto land. | air-breathing and limb-based locomotion. reproduction |
| blastula | hollow sphere of cells, or blastomeres, produced during the development of an embryo by repeated cleavage of a fertilized egg |
| cell aggregrate | a feature of tissue formation that allows the binding of cells of the same type |
| diploblastic | two distinct cell layers, are produced as the embryo develops: - ectoderm and endoderm |
| ectoderm | develops into the outer layer or the epidermis. |
| endoderm | adult diploblastic stage it develops into the gastrodermis (endodermis) and lines the gastrovascular (gastric) cavity |
| gastrula | early multicellular embryo, composed of two or more germinal layers of cells from which the various organs later derive |
| mesoderm | third germ tissue. allows the development of more complex organ systems. |
| radial symmetry | It shows multiple planes of symmetry around a central body axis |
| tripoblastic | three germ layers of tissue. endoderm, ectoderm, mesoderm |
| hydrostatic skeletons | support animals by muscles that act on a fluid-filled cavity. evolved early in multicellular animals – first cnidarians (jellyfish and sea anemones) approximately 600 million years ago |
| Why can gas exchange take place by diffusion in marine flatworms? | The flat shape of these organisms increases the surface area for diffusion, ensuring that each cell within the body is close to the outer membrane surface and has access to oxygen |
| Lungs of non-avian land animals have an enormous surface area, how is this achieved anatomically? | aveoli |
| How does the structure of the respiratory system of birds allow for unidirectional airflow, and what is the advantage relative to tidal flow lungs? | Birds have air sacs that sore and pump air through stationary lungs. Air flow in only one direction because they have one lung. Birds can breathe at much higher elevations than mammals because of their more efficient lung structure. |
| Open circulatory system | heart to other places Smaller animals |
| closed circulatory systems | heart and back larger animals |
| longitudinal muscles | fibres run lengthwise along the body, and the circular fibres encircle it. The body contents are liquids or tissues that can be deformed into different shapes, but they maintain a constant volume. |
| morphospecies concept limitation | members of a species with different phenotypes called polymorphism. some species have different colours and other characteristics. |
| Phylogenetic Species Concept limitation | requires that all members of a species be descendants from a single common but does not specify on what scale this should be applied. |
| exoskeleton | provide hard external support and protection molting |
| disadvantages of exoskeleton | - limit growth of the organism |
| endoskeleton | The rigid bones of vertebrate endoskeleton are jointed for motion and can be repaired if damaged |
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redshre
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