Chapter 8 and 9: Biodiversity and Evolution Flashcards
Evidence of Evolution include:
- fossil records
- comparative anatomy
- comparative embryology
- comparative biochemistry
- geographical distribution
The preserved remains of animals and plants that lived in the past.
Fossils
Examples of animals.
- imprints of plant or animal parts on rocks
- animals trapped and frozen in ice
- insects trapped in a hardened plant resin (amber)
- bones preserved in a peat bog (spongy ground with decaying plants, etc.)
- stone casts of mollusks and animal shells
- wood or giant plant parts replaced by minerals
Where are most fossils formed?
Most fossils were formed at the bottom of shallow bodies of water, where the remains of dead organisms settled to the bottom and were covered by mud or sand that slowly turned into sedimentary rocks.
These are formed in layers stacked on top of another. The oldest fossils were stacked at the bottom, while the most recent ones were stacked on top.
Sedimentary rocks
_ provide most important evidence to compare it with using organisms’ structure and all.
layers of sedimentary rocks
Through this process, scientists reconstruct complete structure of organisms from past.
Fossil Reconstruction
These show that many organisms were very much different from the organisms that exist today. They also show the succession of organisms that is consistent with the stacking of sedimentary rocks from the older to the younger layers.
Fossil records
The rate of decay for each element is steady. Scientists use the unit called _ to measure the rate of decay of an radioactive element. The _ of an element is the time it takes for half of the radioactive element to decay. By determining how much of a particular radioactive element (usually uranium) has changed into a stabilized form (usually lead), scientists can approximate the age or rocks or fossils.
half-life
One way of approximating the age of rocks or fossils. Radioactive elements in rocks or fossils give off radiation at constant known rate, and gradually transform into different elements until they stabilize into an element that no longer emits radiation.
– igneous and metamorphic rocks –
– static-correlation method –
– method of dating rocks and materials using radioactive act.
Radioactive dating
Another method used to date fossils is by _ where most fossils are found. The lowest layers of rocks are the oldest, thus scientists can estimate the age of a fossil by noting its placement in rock layers.
examining sedimentary rocks layers
The sedimentary layers are stacked in order of their ages. This is based on the principle known as the _, which states that in a series of sedimentary rock layers, the younger rocks are normally found on top of older rocks.
law of superposition
Using fossil records, paleontologists are able to trace and reconstruct the transformation of an organism over a span of time. One example is the proposed evolution of the horse. The _, which has been widely known as _ (dawn horses), appeared about 50 million years ago (mya).
Hyracotherium; Eohippus
This provides clues pointing to evolution and common answers. Similar structures evolve.
Comparative Anatomy
Structures that are similar in form and origin, but became modified to adapt to different functions. They have the same basic structure and origin.
homologous structures
In plants, what are the homologous structures?
leaves, petals, sepals, pistils, stamens
Some body parts among different organisms are similar in function, but different in origins. These are?
For examples, the wings of birds, butterflies, and moths are used for flying. Organisms with _ structures may not be closely related.
analogous structures
These are assumed to have lost their primordial functions as species of organisms adapted to changes in their environment. While these organs in some groups of organisms may have lost most or all of their original functions, these organs in other groups of organisms may still be useful and functional.
Vestigial organs
Humans vestigial structures include:
- appendix
- body hairs
- muscles that move ears
- wisdom teeth
This is vestigial, but this organ is a functional structure in herbivores, such as rabbits. It has gradually diminished its function as our ancestors’ diet started to contain less cellulose and food was made more palatable by cooking.
human appendix
According to scientists, embryos appear so similar that it is difficult to tell them apart.
Comparative Embryology
A German biologist noted distinct similarities in the embryological development of fish, reptiles, birds, and mammals. The early stages of growth in all these vertebrates are marked by pharyngeal pouches and tails.
Karl Ernst von Baer (1792-1876)
As the embryos continue to develop, the distinguishing characteristics of each of these species begin to appear. This similarity in the early development of embryos in vertebrates suggests a common ancestry among them.
Comparative Embryology
Perhaps, the most convincing evidence of common descent is the _.
biochemistry of cells
Organic compounds that are found in all cells.
- proteins
- carbohydrates
- lipids
- nucleic acids
This is also a biochemical characteristic common to all organisms.
dependency upon water
When did it become possible to analyze the amino acid sequence of proteins?
1970s
How is it possible to show evolutionary relationships?
Comparing amino acid sequence of similar proteins from a wide variety of organisms makes it possible to show evolutionary relationships.
For example, the human cytochrome c, a mitochondrial protein that is highly conserved across different species, was found to be identical to that of a chimpanzee and to differ by one amino acid from that of a rhesus monkey. This suggests that our biochemical makeup is more closely related to that of the chimpanzee than to that of the rhesus monkey.
What indicates close evolutionary relationship?
Very few differences in the amino acid sequences.
Today, this provides better understanding of a common ancestry. The more closely related two organisms are, the more similar their DNA sequences.
direct sequencing of DNA and RNA
The _ of living things all over the world also provides clues to how species of organisms have changed through time to adapt to changing environmental conditions. Plants or animals that have similar characteristics can be found distributed in previously adjacent continents. Similarities in traits suggest a possible common descent.
Geographical Distribution
Through _ and _, plants or animals have come to inhabit different environments and have evolved along separate lines with different adaptation to their new habitats. Some species of animals, such as whales for example, are adapted to living in water, whereas others, such as dogs and monkeys, are adapted to living on land. Darwin.
migration and isolation
Mechanisms of Evolution include/Mechanisms through which evolution could take place:
- mutation
- natural selection
- migration
- genetic drift
Changes made in the DNA molecules.
Mutation
The process by which organisms with favorable traits suited to an environment have a better chance of surviving or reproducing.
Natural Selection
Natural Selection is classified into:
- Stabilizing Selection
- Directional Selection
- Diversifying Selection
The movement of one population into a habitat previously occupied by another population.
Migration
Changes in the frequency of a gene in a population as a result of chance.
Genetic Drift
DNA replication sometimes results in an error or a failure that changes its code. This may also result in a change in inherited characteristics that may be passed on to the next generation. At other times an external environment agent may trigger this change. Changes made in the DNA molecule through any of these ways is called _.
Mutation
The process by which organisms with favorable traits or traits suited to an environment, have a better chance of surviving and reproducing than those that are not suited. In other words, organisms with favorable traits have a greater chance of passing on their genes to the next generation.
Natural Selection
He observed that reproduction roughly balances with death, illness, accident, and age, and noted the different characteristics even with members of same species — all of these were inherited.
– observable/physical characteristics - many of their variations are because of the inheritance –
He also proposed that offspring whose hierarchy allow them to reproduce and survive well than those less well-adapted (temp., more widespread in subsequent generation). Its idea could change so significantly that a new species can be formed.
Charles Darwin
Charles Darwin explained the five causes of evolutionary change, with each explaining how evolution happens:
- Overpopulation
- Struggle for Existence
- Presence of Variation
- Survival of the Fittest
- Variations can be transmitted
When organisms produce a huge number of offspring that can actually survive, this occurs.
overproduction
This idea of the _ (or more accurately, of the fit enough) is at the core of natural selection.
survival of the fittest
He independently came up with the idea of natural selection and reinforced the claims of Darwin.
Alfred Russel Wallace (1823-1913)
Natural selection and evolution depend on heritable (genetic) variations, which can result from _ or _.
sexual reproduction or mutation
The exchange of segments between homologous chromosomes during meiosis.
Crossing-over
_, which are spontaneous changes in genetic material, can provide the basis for evolutionary changes.
Mutations
A bacterium that causes gonorrhea, a sexually transmitted disease, has rendered it resistant to antibiotics.
Neisseria gonorrhea
The three types of natural selection according to their effects on the distribution of phenotypes within a population.
Stabilizing Selection, Directional Selection, Diversifying Selection
This occurs in most populations where competition is not too strong. It acts against phenotypic extremes by removing these and stabilizing the species toward intermediate phenotypes.
Stabilizing Selection
This results in a population adapting to gradual changes in the environment. The evolution of giraffes from short-necked ancestors to the present long-necked giraffes is a good example. It acts against one extreme phenotype, favoring the other extreme.
Directional Evolution
It caused air pollution which killed the lichens and eventually covered the trees with dark, sooty deposits.
Industrial Revolution
A rare situation in which environmental conditions favor the development of two extreme phenotypes. It acts against intermediate phenotypes. This results when selective pressures are intense, and competition among individuals within a population favors the two extreme phenotypes. The isolating mechanisms that prevent reproduction between evolving subpopulations include geographical barriers (e.g., mountains and oceans), and different breeding times.
Diversifying Evolution
The third process that leads to evolution. The movement of one population of a species into a habitat previously occupied by another population can lead to changes in gene frequency.
Migration
This, along with mutation, natural selection, and migration, is one of the mechanisms of evolution. It refers to changes in the frequency of a gene in a population as a result of chance.
Genetic Drift
An ethical consideration for preserving biodiversity.
“all life depends on uninterrupted functioning of natural systems that ensure the supply of energy and nutrients, so ecological responsibility among all people is necessary for the survival, security, equity, and dignity of the world’s communities”
This includes limiting our consumption of nonrenewable resources to amounts just enough to meet our basic needs. It also includes ensuring that renewable resources are conserved. Taking this will benefit not only the present generation but also the future generations.
Ecological responsibility
This in an ecosystem ultimately limits the amount of organic matter that can be produced. It refers to the amount of energy that is transformed through a food chain. Both energy and nutrients are transferred and transformed through the food chain.
Energy flow
Most of the energy involved in food chains are lost as _. A rough estimate of only about 10% of the energy at each trophic level is made available to organisms occupying the next trophic level. The remaining 90% is lost as _. This means that top level consumers receive the least amount of energy.
heat energy
The ultimate source of energy.
Sun
When it comes to the flow of energy in ecosystems, the two types of organisms involved are?
producers and consumers
They manufacture their own food by converting energy from the environment into chemical energy.
Producers
They depend on other organisms for food.
Consumers
Through this metabolic process, consumers are able to obtain energy from the food they eat.
cellular respiration
Ultimately, all organisms die and become food for _.
decomposers
During _, energy is lost as heat and inorganic nutrients are returned to the soil or water to be used again.
decomposition
Life processes require _. It is the ability of matter to do work.
Energy
Two pathways by which energy enters an ecosystem.
photosynthetic pathway and a pathway involves heat energy being transferred by air, water currents, or convection to warm up the organisms.
Through the photosynthetic pathway, energy is fixed by _, which can synthesize their own food from light energy.
photoautotrophic organisms
They make their own food by metabolizing inorganic matter.
chemoautotrophs
In every ecosystem, it provides a foundation for life and thus puts a limit on the abundance and diversity of life. This is one of the important processes that sustains ecosystems and reflects the dynamics of life.
flow of energy
The process by which a species passes out of _. It is a natural process in our planet’s history. About 90 to 99 percent of all living things that have ever existed on Earth are now extinct. There are countless of species of microorganisms, fungi, plants, and animals that have appeared, survived for a time, and then became extinct.
Extinction
In the past 300 million years or so, human activities, such as _, _, _, and _ have greatly increased the rate of extinction at about 40 to 100 species per day.
hunting, illegal logging, infrastructure building, and farming
These increase the rate of extinction because they change the environment too quickly for the organisms to adapt.
Human activities
When the environment changes for the worse, organisms that have become rare are in danger of becoming extinct and are referred to as _.
endangered species
Three concepts of biological diversity or biodiversity.
Habitat diversity, Species diversity, Genetic diversity
It refers to the diversity of habitats in a given unit of area.
Habitat diversity
It refers to the total number or relative abundance of species.
Species diversity
It refers to the total number of genetic characteristics of a specific species, subspecies, or group of species.
Genetic diversity
This enables populations to adapt to changing environments. The more variations there are in a population, the more likely it is that population possess genetic characteristics that are better adapted to the environment.
Genetic diversity
The study of the factors that influence the size, density, distribution, and growth of a population. It tries to understand and answer how and why population changes over time.
Population ecology
It refers to a group of organisms of the same species that live in a particular area.
Population
Any factor of the environment that limits the size of a population. Diseases and availability of food, water, and shelter are examples of this.
limiting factor
The two most important characteristics of a population.
density and distribution
It refers to the number of individuals per unit area or unit volume. It is a measure of population size.
Population density
A more exact measure defined as the number of individuals per unit of available space.
Ecological density
This, also referred to as population dispersion, is the spatial distribution of individuals of a population.
Population distribution
Three general patterns of population distribution.
random dispersion, regular dispersion, clumped or aggregated dispersion
Individuals in a population are independent of each other because the habitat conditions are relatively uniform all throughout as in a tropical rainforest. Individuals are neither repelled nor attracted to one another. This is not very common in nature.
Random Dispersion
Individuals are about the same distance from one another, often due to competition among individuals in the same population. For example, desert shrubs competing for water often display this type of pattern.
Regular Dispersion
Individuals clump together because resources and suitable habitats may be patchy in distribution. This may be due to daily and seasonal variations in weather conditions, or to the organism’s cyclic reproductive patterns. Individuals may also clump together as a social behavior (e.g., seals clump together for breeding purposes and fish swim in large schools as protection against predators).
Clumped or Aggregated Dispersion
In 1798, this British scholar who is influential in political economy and demography, wrote a book entitled “An Essay on the Principle of Population”. He became known for his theories on population.
Thomas Robert Malthus
According to Malthus, human population has the tendency to increase at a much faster rate than its food supply, which could lead to famine, war, and disease. Several years later, his idea was supported by _, who concluded that the potential of a population to overcome its resources exists in all populations.
Charles Darwin
The change in population size is due to the following factors:
birth (natality), death (mortality), immigration, and emigration
These factors result in an increase in population.
Birth and immigration
These factors result in a decrease in population.
Death and emigration
Both the abiotic and biotic factors in the environment affect the population growth rate. Population ecologists have developed two models to describe the growth of populations:
Exponential Growth and Logistic Growth
The simplest model of population growth that assumes a constant growth rate. Ecologists refer to this growth model as the “J-shaped population growth form” because the resulting graph looks like letter “J”.
Exponential Growth
A more realistic model of population growth where growth rate varies with population size. As a population reaches resource limitations, its growth slows down and stabilizes forming a logistic, sigmoid, or S-shaped graph.
Logistic Growth
The maximum population size of the species that the environment can sustain without getting depleted.
carrying capacity
Limiting factors in populations can be categorized as:
density-dependent or density-independent factors
These affect a population when it reaches a certain density. This includes competition, predation, diseases, parasitism, crowding, and stress factors.
Density-dependent factors
