the change in a population’s genetic makeup over time
the small genetic changes that occur in a population over time
Adaptation or Adaptive Traits
heritable traits that help organisms to survive and reproduce better under prevailing environmental conditions
a species’ way of life in an ecosystem, everything that affects its survival and reproduction 1. The niche includes the members’ adaptations; its range of tolerance for physical and chemical conditions, its interactions with other components of the ecosystem, and its role in energy flow and matter recycling
Species that have broad ecological roles 1. Their living range is broad, includes many different places. 2.
They can eat a variety of foods, and tolerate a wide range of environments.3. If environment is changeable, the generalist will survive better than the specialist
Species that have narrow ecological roles 1. Specialist species can live only in very specific environments.2. This makes them more prone to extinction when environmental conditions change.
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3. If the environment is constant, specialists have fewer competitors.4. Intense competition may lead to evolutionary divergence of a single species into variety of similar species with specialized niches.
two species arise from one when some members of a population cannot breed with other members to produce fertile offspring. Speciation occurs in two phases:1.
Geographic isolation, physical separation for long time periods.2. Reproductive isolation. The gene pools are so changed that members become so different in genetic makeup that they cannot produce fertile offspring.
a significant rise in extinction rates above the background extinction level
a local area’s short-term physical conditions such as temperature and precipitation, typically considered in hours or days
a region’s average weather conditions over a long time, typically considered over decades. Average temperature and average precipitation are the two major factors that determine climate of a region, together with the related factors of latitude and elevation.
where an air mass moves inland from an ocean, reaches a mountain range, and as the air is forced to rise, it cools and loses moisture on the windward side. The leeward side of the mountain will be drier due to the loss of moisture on the windward side
free-floating, weakly swimming, generally one-celled organisms. There are three major types of plankton: phytoplankton (plant plankton), zooplankton (animal plankton)
the upper layer of an aquatic zone where sunlight can penetrate. Clouding or excessive algal growth reduces depth of euphotic zone.
large natural bodies of standing water found in depressions
open, sunlit surface water of a lake away from shore and is the most productive area for food and oxygen production.
Deep oven water of lake that are too dark for photosynthesis. Oxygen levels are lower.
Consists of decomposers and detritus feeders. Fish swim from one zone to another. Sediment washing and dropping detritus feed this area.
A lake that has been newly formed and has a small supply of plant nutrients. They are often deep, crystal-clear blue or green water with low net primary productivity.
has a large or excessive supply of nutrients. Typically is shallow with murky brown or green water with low visibility and high net primary productivity
Lakes between these two extremes (oligotrophic and eutrophic)
Physical appearance of a biological community
the relative sizes, stratification, and distribution of its populations and species
a combination of numbers of different species (richness) and abundance of individuals within each species (species evenness)
the number of ecological niches, their resemblance or difference from each other, and interaction of species with each other
Species that alert us to harmful changes taking place in biological communities.
Species that help ecological communities run smoothly; they determine the type and number of community species.
Species that shape communities by creating and enhancing habitat that benefits other species.
Primary ecological succession
the gradual establishment of biotic communities on lifeless ground; in the soil there is no terrestrial community; in an aquatic community, there is no bottom sediment. This process generally takes a very long time.
Secondary ecological succession
defines a series of communities with different species developing in places with soil or bottom sediment. The soil or sediment remains after the natural community of organisms has been disturbed, removed or destroyed.