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Questions and Answers
What type of plants dominate salt marsh zones?
What is a unique feature of coral reefs?
What is the primary source of energy in shallow ocean zones?
What is the estimated number of species found in coral reefs worldwide?
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What is the primary function of seagrasses in shallow subtidal biological zones?
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What is environmental variation (EV) in ecology?
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What is one way organisms can cope with environmental variation (EV)?
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What is the result of repeated branching events in the evolution of species?
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What type of habitat do mangrove forests form?
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What did Darwin refer to as 'descent with modification'?
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What is the basis of Darwin's concept of natural selection?
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What is a key observation underlying Darwin's concept of natural selection?
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What is a consequence of populations producing more offspring than can survive?
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What is a characteristic of offspring in any generation?
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What is the ultimate outcome of the process of natural selection?
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What is a key feature of the 'tree' of life?
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What is the underlying mechanism that explains the diversity of present-day life forms?
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What is microevolution?
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What can lead to a change in gene frequency in a population?
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What is an example of microevolution?
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What is the outcome of macroevolution?
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How do humans contribute to evolutionary change?
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What is the outcome of accumulation of small changes in populations over time?
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What is an example of macroevolution?
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What is a characteristic of species with a Type II survivorship curve?
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What is an example of a species that follows a Type III survivorship curve?
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What is the main difference between R-selected species and K-selected species?
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What is the term for the strategy that focuses on increasing the quantity of offspring at the expense of individual parental investment?
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Which of the following species is an example of a K-strategist?
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What is the term for the pattern of survivorship that reflects the life history of a population?
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What is the term for species that do not follow either an R-selected or K-selected strategy?
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What is the primary difference between opportunistic species and equilibrium species?
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What is the term for the process that slows and eventually halts population growth?
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What is the term for the maximum rate of population growth possible in ideal conditions?
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What type of growth pattern occurs when environmental resistance limits population growth?
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What is the term for the impact of the environment on population growth?
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What is the shape of the growth curve in logistic growth?
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What is the term for the individual contribution to population growth?
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What happens to the per capita growth rate as population size approaches a maximum?
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Study Notes
Shallow Ocean Zones
- Shallow ocean zones are diverse and productive due to sufficient light near the shoreline, allowing for the establishment of photosynthetic organisms.
- These organisms provide energy to support large communities of animals and microorganisms.
Salt Marshes
- Salt marshes are shallow marsh zones dominated by emergent vascular plants, mainly grasses, rushes, and herbs.
- They are home to a variety of animals, including fish, crabs, birds, and mammals.
Mangrove Forests
- Mangrove forests are woody plants that inhabit shallow coastal estuaries.
- They provide a habitat for many marine and terrestrial animals, including monitor lizards, fishing cats, crab-eating monkeys, shrimps, and fishes.
Coral Reefs
- Coral reefs are formed in shallow ocean waters by corals, which are animals related to jellyfish that live in close association with algal partners, forming large colonies.
- By extracting calcium carbonate from seawater, they form skeleton-like structures that pile up to form reefs.
- Coral reefs create a unique, structurally complex habitat that supports a rich marine community, with as many as 1 million species found worldwide, including 4,000 fish species.
Seagrass Beds
- Seagrass beds are shallow, subtidal biological zones that are not related to the grass family but are morphologically similar.
- They live in shallow waters (< 5 m) and provide a habitat for various marine species.
Coping with Environmental Variation
- Environmental Variation (EV) refers to temporal and/or spatial changes in environmental conditions.
- Organisms have two options for coping with EV: tolerance or avoidance.
- Tolerance is the ability of organisms to endure unfavorable environmental conditions.
- Avoidance involves minimizing the adverse effects of EV on the organism.
Evolution
- Evolution is the process of change in organisms over time, resulting in the diversity of life forms.
- It involves two mechanisms: natural selection and genetic drift.
- Natural selection is the process by which populations evolve to become better suited to their environments over time.
- Darwin's concept of natural selection was based on several key observations:
- Traits are often heritable.
- More offspring are produced than can survive.
- Offspring vary in their heritable traits.
- Microevolution is a change in gene frequency within a population, which can be observed over short periods of time.
- Macroevolution occurs when populations accumulate differences over time, leading to the formation of new species.
Human Contribution to Evolutionary Change
- Humans contribute to evolutionary change through activities such as pesticide use, leading to the development of resistant species.
- Examples of microevolution include:
- Mosquitoes evolving resistance to DDT.
- Whiteflies evolving resistance to pesticides.
- Gonorrhoeal bacteria strains evolving resistance to penicillin.
- HIV strains evolving resistance to antiviral medicines.
Patterns of Survivorship in Populations
- There are three types of survivorship curves:
- Type I curve: most deaths occur at old ages.
- Type II curve: the chances of surviving are the same for any particular age group.
- Type III curve: most deaths occur at the early stages of life and survival increases with age.
Selection Strategies
- Selection strategies relate to the selection of combinations of traits in an organism that trade-off between quantity or quality of offspring.
- There are three types of strategies:
- Opportunistic species (R-selected): they have a short lifespan, small stature, and produce many offspring to take advantage of new resources.
- Equilibrium species (K-selected): they live longer, are larger, and produce fewer young but have greater parental care.
- Continuous spectrum: species that do not follow either R or K strategy.
Density-Dependent Population Regulation
- As populations grow, there is overcrowding, which reduces access to food and other resources for individuals and their offspring.
- This leads to social strife, disease spread, and predation, slowing down population growth.
- This process is known as density-dependent population regulation, which decreases per capita growth rate with increasing population size.
Environmental Resistance
- Environmental resistance (ER) sets a limit to the potential/intrinsic rate of increase of a population.
- ER occurs when most environments restrict growth, and exponential growth cannot continue indefinitely.
- This leads to a new set of growth patterns, known as logistic growth.
Logistic Growth
- Logistic growth occurs when the population's per capita growth rate gets smaller and smaller as population size approaches a maximum imposed by limited resources in the environment.
- It results in an S-shaped (sigmoid) growth curve with four phases:
- The lag phase.
- The exponential growth phase.
- The deceleration phase.
- The stationary phase.
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Description
Explore the diverse and productive shallow ocean zones, including salt marshes and mangrove forests, and their inhabitants such as fish, crabs, birds, and mammals.
