[1] Although biogeography traditionally focused on plants and larger animals, recent studies have broadened this field to include distribution patterns of microorganisms.
For macro-organisms, biogeographical patterns (i.e., which organism assemblages appear in specific places and times) appear to arise from both past and current environments.
For example, polar bears live in the Arctic but not the Antarctic, while the reverse is true for penguins; although both polar bears and penguins have adapted to cold climates over many generations (the result of past environments), the distance and warmer climates between the north and south poles prevent these species from spreading to the opposite hemisphere (the result of current environments).
[citation needed] The biogeography of microorganisms (i.e., organisms that cannot be seen with the naked eye, such as fungi and bacteria) is an emerging field enabled by ongoing advancements in genetic technologies, in particular cheaper DNA sequencing with higher throughput that now allows analysis of global datasets on microbial biology at the molecular level.
When scientists began studying microbial biogeography, they anticipated a lack of biogeographic patterns due to the high dispersibility and large population sizes of microbes, which were expected to ultimately render geographical distance irrelevant.
[13][14] This is surprising given the many disparities between microorganisms and macro-organisms, in particular their size (micrometers vs. meters), time between generations (minutes vs. years), and dispersibility (global vs. local).
In contrast, studies on indoor fungal communities[14] and global topsoil microbiomes[17] found microbial biodiversity to be significantly higher in temperate zones than in the tropics.
In contrast, a study on marine surface bacteria[15] showed not only a latitude gradient, but also complementarity distributions with similar populations at both poles, suggesting no "isolation by geographic distance".
Panspermia assumes that life can survive the harsh space environment, which features vacuum conditions, intense radiation, extreme temperatures, and a dearth of available nutrients.
[25] Thus microbial biogeography can be applied to panspermia as it predicts that microbes are able to protect themselves from the harsh space environment, know to emerge when conditions are safe, and also take advantage of their dormancy capability to enhance biodiversity wherever they may land.