Paleoecology
Shedding light on the
paleocommunities preserved in amber is
critical to understand the associated
conifer forest paleoecosystem. A reliable,
multiscale reconstruction of this
paleoecosystem represents the ultimate goal
of the AMBARES project, resulting from the
integration of all the available geological
and paleobiological data, and taking into
account possible taphonomical biases. The
study of the paleobiological content in the
Spanish ambers has identified ecological
relationships between different organisms,
illustrating their ecology, behavior, and
biotic interactions. Within these, the study
of amber inclusions related with aquatic
environments and plant-insect interactions
are especially informative.
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Although the presence of
aquatic arthropods in amber is exceptional,
adults with aquatic juvenile stages, like
those of heteropterans, plecopterans,
chironomid dipterans, and trichopterans, are
quite common. The presence of these groups
is able to suggest the relative proximity of
water bodies, namely seasonal ponds, rivers,
and small water bodies in the forest (for
instance, inside trunks), to the resin-producing
areas in the paleoecosystem. The presence of
other groups, like ceratopogonid dipterans,
is able to suggest the proximity of the sea
to the resin-producing areas. The diversity
and relative abundance of arthropod groups
with paleoenvironmental significance is
being compared with data from other amber
outcrops and modern forests. Moreover, the
relative abundance of certain arthropod
groups can provide specific paleoecological
information. For instance, the number of
snake-flies (Raphidioptera) in Spanish amber
is about ten times higher than in the rest
of main Cretaceous ambers, a fact that has
been linked with the important role that
paleofires played in the Spanish amber
forest.
The principal
interespecific biotic interactions found in
Spanish amber so far include mating, which
represents the most direct way to identify
males and females from a given species, and
swarming (nuptial flight) behaviour, also
valuable for sex identification. The study
on interespecific biotic interactions, in
turn, is currently focused on plant-insect
interactions. This field has already
provided remarkable discoveries, like two
thrips species (Thysanoptera) with pollen
grains adhered to specialized body setae and
proven to be gymnosperm pollinators, and the
tight relationship (perhaps a mutualism)
between a green lacewing larva (Chrysopoidea)
and a fern, the insect feeding on the fern’s
herbivores and the fern providing trichomes
for the insect’s defense (camouflage and
physical protection). Moreover, insects with
elongated mouthparts could have fed on
nectar, as occurs with some dipterans and
neuropterans. Some of these insects most
likely acted as pollinators. Other
interspecific biotic interactions include
prey-predator relationships, the best
examples of which are spider webs with
trapped insects, or parasitism, like
parasitic mites attached with their
mouthparts to their dipteran hosts while
feeding on them. The study of parasites/parasitoids,
like some wasps, can also provide
information on their host and hence holds
the potential to provide information about
organisms not directly preserved in the
amber fossil record. |