events, which have been described in detail in other chapters of this book; we will
only briefly mention the most important events related to the historical relationship
of the Alboran biota with those of other parts of the world.
With the word macroecology, we mean the study of ecological processes that
occur at geographical, temporal, and taxonomical scales beyond the scope of
experimental tests, normally approaching relationships between organisms and
their environment in a regional or global context (Brown and Maurer 1989). The
study of the effect of the regional climatic variability in the distribution pattern of
species is part of macroecology, as it is also the analyses of the several large-scale
gradients in species diversity. We will address the main internal geographical trends
in species richness, mainly the bathymetrical gradient, but also the less significant
longitudinal and latitudinal ones. The effect of large-scale macroclimatic patterns,
such as those derived from the North Atlantic Oscillation and the Arctic Oscillation,
on Alboran waters and their consequences for living beings and fishing activities will
be also addressed here. The analyses of recent changes in Alboran biota, resulting
from the invasion of alien species, are also of interest from a macroecological and
biogeographical point of view.
In spite of the importance of the Alboran Sea from a biogeographic and
macroecological point of view, there are no integrating works of the entire biota.
This is crucial, since species are typically interrelated, and it is necessary to approach
the biogeography and macroecology of the complete flora and fauna in order to
obtain comprehensive descriptive, explanatory, and predictive conceptual models of
Alboran biodiversity, ecosystems, and natural resources.
11.2 Historical Biogeography: Where Do the Biota
of the Alboran Sea Come From?
The current patterns of biodiversity in the Alboran Sea can only be understood in the
light of the very complex geological history of the Mediterranean Sea as a whole.
The early history of this sea may be considered to start in the Mesozoic era, some
150 My BP, when the supercontinent of Gondwana, then migrating to the Southern
Hemisphere, was separated from Eurasia by a large ocean named Tethys by geologists. As a result of the breakup of the Gondwana landmass, Africa separated from
South America about 100 My BP, started moving towards Eurasia, and the large
Tethys Ocean went consequently under compression, gradually becoming a Tethys
Sea. The current configuration of the biota in the Alboran Sea and adjacent waters is
the result of how this common Tethyan heritage was overcome by later events.
The essential point, from a biogeographical perspective, is that throughout the
Cretaceous (145–66 My BP) and the Paleogene (66–23 My BP) periods the tropical
and subtropical world ocean had easy and permanent East-West communication.
The part of the Tethys Sea corresponding to the present-day Mediterranean communicated eastwards with the Indian Ocean through the current Middle East, Mesopotamia, and the Persian Gulf. To the West, there was a broad communication towards
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R. Real et al.
only briefly mention the most important events related to the historical relationship
of the Alboran biota with those of other parts of the world.
With the word macroecology, we mean the study of ecological processes that
occur at geographical, temporal, and taxonomical scales beyond the scope of
experimental tests, normally approaching relationships between organisms and
their environment in a regional or global context (Brown and Maurer 1989). The
study of the effect of the regional climatic variability in the distribution pattern of
species is part of macroecology, as it is also the analyses of the several large-scale
gradients in species diversity. We will address the main internal geographical trends
in species richness, mainly the bathymetrical gradient, but also the less significant
longitudinal and latitudinal ones. The effect of large-scale macroclimatic patterns,
such as those derived from the North Atlantic Oscillation and the Arctic Oscillation,
on Alboran waters and their consequences for living beings and fishing activities will
be also addressed here. The analyses of recent changes in Alboran biota, resulting
from the invasion of alien species, are also of interest from a macroecological and
biogeographical point of view.
In spite of the importance of the Alboran Sea from a biogeographic and
macroecological point of view, there are no integrating works of the entire biota.
This is crucial, since species are typically interrelated, and it is necessary to approach
the biogeography and macroecology of the complete flora and fauna in order to
obtain comprehensive descriptive, explanatory, and predictive conceptual models of
Alboran biodiversity, ecosystems, and natural resources.
11.2 Historical Biogeography: Where Do the Biota
of the Alboran Sea Come From?
The current patterns of biodiversity in the Alboran Sea can only be understood in the
light of the very complex geological history of the Mediterranean Sea as a whole.
The early history of this sea may be considered to start in the Mesozoic era, some
150 My BP, when the supercontinent of Gondwana, then migrating to the Southern
Hemisphere, was separated from Eurasia by a large ocean named Tethys by geologists. As a result of the breakup of the Gondwana landmass, Africa separated from
South America about 100 My BP, started moving towards Eurasia, and the large
Tethys Ocean went consequently under compression, gradually becoming a Tethys
Sea. The current configuration of the biota in the Alboran Sea and adjacent waters is
the result of how this common Tethyan heritage was overcome by later events.
The essential point, from a biogeographical perspective, is that throughout the
Cretaceous (145–66 My BP) and the Paleogene (66–23 My BP) periods the tropical
and subtropical world ocean had easy and permanent East-West communication.
The part of the Tethys Sea corresponding to the present-day Mediterranean communicated eastwards with the Indian Ocean through the current Middle East, Mesopotamia, and the Persian Gulf. To the West, there was a broad communication towards
432
R. Real et al.