The increase in species richness or biodiversity that occurs from the poles to the tropics, often referred to as the latitudinal diversity gradient (LDG), is one of the most widely recognized patterns in ecology.
 Put another way, in the present day localities at lower latitudes generally have more species than localities at higher latitudes.
 The LDG has been observed to varying degrees in Earth's past.
The Corethrellidae are a family of parasitic midges, small flying insects belonging to the order Diptera, that are commonly known to parasitize frogs.
 The members of the family are sometimes known as "frog-biting midges".
 The family currently consists of just two genera, totalling around 97 species worldwide.
 Several fossil species are known.
 Most extant species are found in the lower latitudes, usually associated around the tropics.
Rapoport's rule is an ecogeographical rule that states that latitudinal ranges of plants and animals are generally smaller at lower latitudes than at higher latitudes.
Calycanthus (sweetshrub) is a genus of flowering plants in the family Calycanthaceae, endemic to North America.
 The genus includes two to four species depending on taxonomic interpretation; two are accepted by the "Flora of North America".
The stratosphere ( ) is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere.
 About 20% of the atmosphere's mass is contained in the stratosphere.
 The stratosphere is stratified in temperature, with warmer layers higher and cooler layers closer to the Earth.
 The increase of temperature with altitude is a result of the absorption of the Sun's ultraviolet radiation by the ozone layer.
 This is in contrast to the troposphere, near the Earth's surface, where temperature decreases with altitude.
 The border between the troposphere and stratosphere, the tropopause, marks where this temperature inversion begins.
 Near the equator, the stratosphere starts at 18 km ; at mid latitudes, it starts at 10 - and ends at 50 km ; at the poles, it starts at about 8 km .
 Temperatures vary within the stratosphere with the seasons, in particular with the polar night (winter).
 The greatest variation of temperature takes place over the poles in the lower stratosphere; variations at lower latitudes and higher altitudes are smaller.
Anacardium is a genus of flowering plants in the family Anacardiaceae, native to tropical regions of the Americas.
The tripodfish or tripod spiderfish, "Bathypterois grallator", is a deep-sea benthic fish in the Ipnopidae family found at lower latitudes.
 It is now relatively well known from photographs and submersible observations, and seem to prefer to perch on the ooze using much elongated fin rays in the tail and two pelvic fins to stand, facing upstream with the pectoral fins turned forward so the outthrust projecting fin rays resemble multiple antennae, and are indeed used as tactile organs.
 "B. grallator" is hermaphroditic.
 At least 18 species are placed in the genus "Bathypterois", several of which have similar appearance and behavior to "B. grallator".
 "B. grallator" is the largest member of its genus, commonly exceeding a standard length of 30 cm and reaching up to 43.4 cm .
In geology, permafrost is ground, including rock or (cryotic) soil, at or below the freezing point of water 0 C for two or more years.
 Most permafrost is located in high latitudes (in and around the Arctic and Antarctic regions), but alpine permafrost may exist at high altitudes in much lower latitudes.
 Ground ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of the ground material.
 Permafrost accounts for 0.022% of total water on Earth and exists in 24% of exposed land in the Northern Hemisphere.
 It also occurs subsea on the continental shelves of the continents surrounding the Arctic Ocean, portions of which were exposed during the last glacial period, with global weather implications.
The common thresher ("Alopias vulpinus"), also known by many names such as Atlantic thresher, big-eye thresher, fox shark, green thresher, swingletail, slasher, swiveltail, thintail thresher, whip-tailed shark and Zorro thresher shark, is the largest species of thresher shark, family Alopiidae, reaching some 6 m in length.
 About half of its length consists of the elongated upper lobe of its caudal fin.
 With a streamlined body, short pointed snout, and modestly sized eyes, the common thresher resembles (and has often been confused with) the pelagic thresher ("A. pelagicus").
 It can be distinguished from the latter species by the white of its belly extending in a band over the bases of its pectoral fins.
 The common thresher is distributed worldwide in tropical and temperate waters, though it prefers cooler temperatures.
 It can be found both close to shore and in the open ocean, from the surface to a depth of 550 m .
 It is seasonally migratory and spends summers at lower latitudes.
The subtropical ridge, also known as the subtropical high or horse latitudes, is a significant belt of atmospheric high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere.
 It is the product of the global air circulation cell known as the Hadley Cell.
 The subtropical ridge is characterized by mostly calm winds, which act to reduce air quality under its axis by causing fog overnight, and haze during daylight hours as a result of the stable atmosphere found near its location.
 The air descending from the upper troposphere flows out from its center at surface level toward the upper and lower latitudes of each hemisphere, creating both the trade winds and the westerlies.
 The subtropical ridge moves poleward during the summer, reaching its most northern latitude in early fall, before moving equatorward during the cold season.
 The El Niño southern climate oscillation (ENSO) can displace the northern hemisphere subtropical ridge, with La Niñas allowing for a more northerly axis for the ridge, while El Niños show flatter, more southerly ridges.
 The change of the ridge position during ENSO cycles changes the tracks of tropical cyclones that form around their equatorward and western peripheries.
 As the subtropical ridge varies in position and strength, it can enhance or depress monsoon regimes around their low-latitude periphery.
 The term "horse latitudes" refers to and is synonymous with the subtropical ridge or subtropical high.

Question: Which plants are found in the lower latitudes, Calycanthus or Anacardium?
Answer: Anacardium