A large river can act as a barrier that prevents gene flow between populations of small rodents on either side, leading to genetic isolation and eventually speciation. Small rodents are typically poor dispersers and may struggle to cross physical barriers like rivers. Birds, on the other hand, are often strong fliers and can easily fly over barriers like rivers, allowing for gene flow between populations and preventing the formation of new species.
IgG is the only antibody small enough to cross he placenta.
Dogs cannot get most viruses carried by humans as these viruses cannot cross the species barrier. Deadly viruses like rabies can cross the barrier between species, but are more often transmitted from the dog to the human. A common misconception is that dogs can catch a cold or flu from their owners but this is untrue
a prezygotic barrier
The Great Barrier Reef poses no threat to any species. It is the species that already live within the waters of the Great Barrier Reef that are under threat from external sources.
Netilmicin does not cross the blood-brain barrier.
According to the Great Barrier Reef Marine Park Authority, there are about 1625 species of fish that live in and around the Great Barrier Reef, not including the shark species. Of these, 1400 are coral reef species. In addition, there are over 3000 species of molluscs, 630 species of echinoderm such as starfish and sea urchins, 14 known species of sea snakes, 30 species of whales and dolphins, dugongs and 133 species of sharks and rays.
Yes. Valium (diazepam) does indeed cross the blood brain barrier. It is one of the more lipophilic of the benzodiazepine medications.
We just have one more barrier to cross; then we can lay siege to the castle.
It might also be instrumental in the evolution of a new species of bird. With birds, however, the impact of such a barrier will usually be much smaller, as birds can more easily cross such barriers and therefore maintain a high interbreeding frequency. The decline of interbreeding frequency is what causes subpopulations to diverge, sometimes culminating in speciation.
Yes
It is water soluble...