Chapter 20 Key Concepts

Although local patterns of species diversity are often explained in terms of short-term dynamic interactions, regional patterns are probably as much explained by the balance of speciation and extinction.
Habitat change or destruction, widespread diseases, biological interactions, or random fluctuations of population size may cause extinction.
Geographic isolation and major geographic gradients in temperature and salinity combine to determine provinces of statistically distinct groupings of species.
The relation of geography to speciation can be accomplished by relating evolutionary trees to patterns of geographic occurrence.
The geographic history of a region and major ocean basins is a crucial background for the evolution of marine species and the origin of marine biodiversity patterns.
A geographic barrier may isolate populations of just one species, or it may isolate recently evolved, closely related species or groups of species of a variety of distantly related groups.
Evolutionary lineages are more isolated and regionally diversified in the sea than has been previously thought, especially among islands on archipelagos and newly appearing islands.
Biodiversity is an accounting of species within and across habitats.
Species diversity tends to increase with decreasing latitude.
There are differences in species diversity between ocean basins.
Within the Pacific Ocean, species diversity in coral reefs declines in all directions from an Indo-Pacific diversity maximum.
Inshore and estuarine habitats are poorer in species than comparable habitats in the open sea.
Complex recent historical events may explain some current regional differences in species diversity.
Many regional differences arose millions of years ago and have persisted.
The pattern of species appearances within the latitudinal diversity gradient fits a model of tropical origins and spread to higher latitudes.
On a global scale, temperature is the best explanation for maximum diversity, but the explanation for this is not clear.
The maximum of diversity in the Indo-West Pacific is probably the result of a combination of processes. Species diversity increases with increasing habitat area.
Increasing long-term habitat stability may tip the speciation-extinction balance toward higher species diversity.
The fossil record allows us to distinguish periods of origin and extinction. During the Phanerozoic Eon, there have been periods of rapid expansion and several episodes of major extinction.
A great deal of the total diversity of marine life is as yet unknown.
Diversity may increase overall biological productivity and the potential for resilience in an ecosystem in the face of environmental change, and also may have the value of providing more sources of drugs and other products.
Many marine habitats have been strongly altered by human activity. The reduction of diversity often leads to an incorrect perception of what is natural.
Marine biodiversity may be reduced by habitat destruction, habitat fragmentation, and habitat degradation. Is extinction possible in the wide ocean?
The species-area effect might be used to predict the loss of species, but an understanding of habitat and biogeographic effects is crucial as well.
Conservation remedies can be managed from the perspective of ecosystem function and ecosystem services.
Biodiversity has a role in ecosystem function and ecosystem services.
Marine protected areas have been established to protect marine biodiversity, but relatively little habitat is under protection, and local practices do not always result in complete protection.
Genetic approaches can be used to identify species and genetically distinct populations within species.
Laws are now being used to protect both biodiversity and habitats.
Many invasions are facilitated by human transport, and introductions of ecologically potent species may cause local extinctions and a homogenization of the world marine biota.
Invaders probably rarely establish successful populations and usually become extinct, but vectors, high invasion frequency, and ecological suitability of the target habitat all contribute to invasion success.
Marine invasions are common, and invaders often come to dominate their newly adopted homes.
In recent years, the ballast water of ships has greatly accelerated transport of exotic species across oceans. Although transoceanic dispersal of marine larvae certainly occurs occasionally, shipping is currently a far more frequent source of movement.
Habitats vulnerable to invasion might include those that are disturbed.
Invasive species might be more efficiently repelled in tropical environments, owing to high predation rates and high diversity. Canals may be a source of large-scale invasions.