From LiveScience, with different hyperlinks there:
The discovery of the oldest bee fossil supports the theory that bees.evolved from wasps, scientists reported today.See also here.The 100 million-year-old fossil was found in a mine in the Hukawng Valley of Myanmar (Burma) and preserved in amber.
Amber, which begins as tree sap, often traps insects and plant structures before they fossilize.
“This is the oldest known bee we’ve ever been able to identify, and it shares some of the features of wasps,” said lead author George Poinar, a researcher from Oregon State University.
“But overall it’s more bee than wasp, and gives us a pretty good idea of when these two types of insects were separating on their evolutionary paths.”
The quarter-inch fossil shares traits of the carnivorous wasp such as narrow hind legs while exhibiting branched hairs on its leg, a characteristic of the modern bee that allows pollen collection.
Around the same time the bee was trapped, plants that rely on mechanisms other than the wind to spread their seeds, started expanding and diversifying.
Prior to that, the world was mostly green with conifer trees that depended on the wind for pollination.
“Flowering plants are very important in the evolution of life,” Poinar said.
Honeybee decline: here.
Asian giant honeybees: here.
Eocene fossil bee from France: here.
Carpenter bees of Singapore: here.
How are different insects related to each other, according to DNA research? See here.
Ants: here.
Underwanter ants of Australia: here.
Hymenoptera evolution: here.
Evolution of amoebas: here.
Genomics: On the Genome of a Social Insect.
The transformation of an insect species from a solitary lifestyle
to advanced colonial existence requires alterations in every
system of the body, coupled with sufficient plasticity in the
traits prescribed by the genes to generate strong differences
among the adult castes. A picture of this revolution at the
genomic level appears in new work…
Full report at http://scienceweek.com/2006/sw061103.htm
Comment by Administrator — November 2, 2006 @ 3:13 pm
EVOLUTION: ON THE ORIGIN OF INSECTS
The following points are made by H. Glenner et al (Science 2006
314:1883):
1) Although hexapods — those arthropods having six legs,
including insects — are the most diverse group of contemporary
animals in terms of biological niches and number of species,
their origin is highly debated. A key problem is the almost
complete absence of fossils that connect hexapods to the other
major arthropod sub-phyla, namely Crustacea, Myriapoda (such as
centipedes and millipedes), and Chelicerata (such as scorpions
and spiders). Over the years, hexapods (insects, springtails,
proturnas, and diplurans) have been phylogenetically linked to
all of these major arthropod taxa (1).
2) Traditionally, hexapods and the multi-legged myriapods have
been united in a group named Atelocerata on the basis of
morphological similarities between their tracheal respiration
systems and head appendages. However, recent evidence from
phylogenetic analyses of molecular sequence data from a variety
of genes, as well as from newer morphological studies, points to
a relationship between hexapods and crustaceans (2-5), a grouping
commonly referred to as Pancrustacea. Furthermore, studies on
neurological development in the major arthropod groups have
pointed out similarities between the myriapods and chelicerates.
Hence, pancrustacean monophyly seems to be gaining more support.
So, what does this view tell us about the possible origin of
hexapods?
3) The crustaceans are recorded at least as far back as the Upper
Cambrian, about 511 million years ago, where they are found in
marine sediments. However, except for the debated Devonohexapodus
bocksbergensis specimen, all hexapod remains are found only in
freshwater or terrestrial strata no earlier than the Devonian,
around 410 million years ago. This leaves a gap of 100 million
years to the earliest crustaceans. The common explanation has
been that earlier traces of hexapods have been erased from the
fossil record and that hexapods, like other major groups of
terrestrial animals, have closely related ancestors to be found
in the marine environment.
4) The recent morphological and molecular-based studies suggest
an alternative interpretation — that hexapods originated within
the crustaceans rather than as a sister group. Although the
morphological studies mainly favor a close phylogenetic
connection between hexapods and malacostracan crustaceans (crabs
and crayfish), recent molecular sequence data suggest that
hexapods are closely related to branchiopods, a freshwater
dwelling group of crustaceans that includes water fleas and fairy
shrimp. This hypothesis is supported by analysis of Hox genes
that demonstrates homology between development of the pregenital
trunk region in insects and the thorax in branchiopods. The new
molecular results correspond well with the fossil record and
suggest an evolutionary origin of the hexapods in freshwater
around 410 million years ago rather than in the marine Cambrian
environment.
References (abridged):
1. G. Giribet, C. Ribera, Cladistics 16, 204 (2000).
2. J. M. Mallatt et al., Mol. Phy. Evol. 31, 178 (2004).
3. J. C. Regier, J. W. Shultz, Mol. Phy. Evol. 20, 136 (2001).
4. J. W. Shultz, J. C. Regier, Proc. R. Soc. London Ser. B 267,
1011 (2000).
5. U. W. Hwang et al., Nature 413, 154 (2001).
Science http://www.sciencemag.org
ScienceWeek http://scienceweek.com
Comment by Administrator — December 28, 2006 @ 10:46 pm
Mystery illness killing honeybees:
A mysterious disease is killing many honeybee
colonies across the U.S., threatening honey
production and possibly crops.
http://www.world-science.net/othernews/070228_bees.htm
Comment by Administrator — March 2, 2007 @ 2:25 pm