Marine Ecosystems: Salt Marshes and Mangrove Forests

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39 Questions

What type of plants dominate salt marsh zones?

Emergent vascular plants

What is a unique feature of coral reefs?

They are formed by extracting calcium carbonate from sea water

What is the primary source of energy in shallow ocean zones?

Photosynthetic organisms

What is the estimated number of species found in coral reefs worldwide?

1 million

What is the primary function of seagrasses in shallow subtidal biological zones?

To provide habitat for marine animals

What is environmental variation (EV) in ecology?

Temporal and/or spatial changes in environmental conditions

What is one way organisms can cope with environmental variation (EV)?

Tolerance

What is the result of repeated branching events in the evolution of species?

A multi-level 'tree' linking all living organisms

What type of habitat do mangrove forests form?

Shallow coastal estuaries

What did Darwin refer to as 'descent with modification'?

The evolution of species over time

What is the basis of Darwin's concept of natural selection?

The variation of traits in a population

What is a key observation underlying Darwin's concept of natural selection?

Traits are often heritable

What is a consequence of populations producing more offspring than can survive?

Competition for limited resources in each generation

What is a characteristic of offspring in any generation?

They vary in their heritable traits

What is the ultimate outcome of the process of natural selection?

Populations that are better suited to their environments

What is a key feature of the 'tree' of life?

It is a hierarchical, branching structure

What is the underlying mechanism that explains the diversity of present-day life forms?

Natural selection

What is microevolution?

A change in gene frequency within a population

What can lead to a change in gene frequency in a population?

Natural selection, immigration, mutation, and genetic drift

What is an example of microevolution?

The development of antibiotic resistance in bacteria

What is the outcome of macroevolution?

The formation of a new species

How do humans contribute to evolutionary change?

By creating artificial selection pressures

What is the outcome of accumulation of small changes in populations over time?

Macroevolution

What is an example of macroevolution?

The evolution of whales from land mammals

What is a characteristic of species with a Type II survivorship curve?

Survival rates are the same for any particular age group

What is an example of a species that follows a Type III survivorship curve?

Oysters

What is the main difference between R-selected species and K-selected species?

R-selected species have a shorter lifespan and produce many offspring, while K-selected species live longer and produce few offspring

What is the term for the strategy that focuses on increasing the quantity of offspring at the expense of individual parental investment?

R-selection strategy

Which of the following species is an example of a K-strategist?

Trees

What is the term for the pattern of survivorship that reflects the life history of a population?

Selection strategy

What is the term for species that do not follow either an R-selected or K-selected strategy?

Continuous spectrum species

What is the primary difference between opportunistic species and equilibrium species?

The number of offspring produced and parental investment

What is the term for the process that slows and eventually halts population growth?

Density Dependent

What is the term for the maximum rate of population growth possible in ideal conditions?

Intrinsic Rate of Increase

What type of growth pattern occurs when environmental resistance limits population growth?

Logistic Growth

What is the term for the impact of the environment on population growth?

Environmental Resistance

What is the shape of the growth curve in logistic growth?

S-shaped

What is the term for the individual contribution to population growth?

Per Capita Growth Rate

What happens to the per capita growth rate as population size approaches a maximum?

It decreases

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.

Explore the diverse and productive shallow ocean zones, including salt marshes and mangrove forests, and their inhabitants such as fish, crabs, birds, and mammals.

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