Why does Brazil appear to have a low endemism rate?

Nature Talk
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Brazil is always lauded as the world’s most biodiverse country, with many endemic species. I slightly roll my eyes because of one question: how many Brazilian endemic species can you name? Probably Leontopithecus rosalia and not much else. Endemism rates seem to be highest in Australia, Madagascar and South Africa (my country). For plants, the former two have 80-90% endemism rate and South Africa around 65%. But Brazil is not too far behind with 56%

But consider this. Anyone casually into botany should be able to name some endemic plants from those other three countries. For example:

Australia - Acacia pycnantha, Eucalyptus regnans, Caleana major
Madagascar - Adansonia grandidieri, Ravenala madagascariensis, Angraecum sesquipedale
South Africa - Protea cynaroides, Strelitzia reginae, Disa uniflora

But I’m not sure many could name one Brazilian endemic species if its not their speciality.

I looked up the top 10 most observed native species on iNaturalist from the three biggest plant families for each of the four countries. How many of the ten were endemic to the country for each family?

Asteraceae
South Africa - 7, Madagascar - 9, Australia - 8, Brazil - 0

Orchidaceae
South Africa - 8, Madagascar - 7, Australia - 9, Brazil - 3

Fabaceae
South Africa - 7, Madagascar - 7, Australia - 10, Brazil - 2

Brazil is way behind the others. Why with a high endemism rate, are Brazil’s endemics so unknown and unobserved?

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My guess is it is because Australia, Madagascar, and South Africa are all kind of ‘islands’ of their own ecosystem (South Africa isn’t an island obviously but is a patch of mediterranean ecosystem surrounded by ocean and desert). Whereas Brazil has rain forest and other ecosystems that also extend into other countries. Most species in the Amazon don’t stop at that border, for instance

Endemicism as defined by political or cultural boundaries isn’t that ecologically meaningful. If you look at the ‘amazon rain forest’ area, the endemism must be through the roof, similar to Australia, right? But since that rain forest extends into other countries msot of it doesn’t result in ‘Brazil endemics’.

Also when you apply to a whole continent (Australia) or vast region (the Amazon), endemicism kind of loses its meaning. Everything, so far as we know, is endemic to Earth. Where it really gets meaningful is on the scale of individual mountain ranges, lakes, small islands, etc. Otherwise it’s just the normal distribution of species which is always going to be finite.

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I understand all those things, but that doesn’t explain the peculiar data I fished there. If more than half of Brazil’s plant species are endemic, why are only 5 of the 30 species I picked endemic? My choice must have been biased but why would Brazil’s most observed species be less likely to be endemic? And why is this not the case for the others?

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Well, if you are going by ‘most observed’ species, these tend to be generalists (wide distribution) that live near populated areas, not specialized species (more likely to have a restricted range) that live in less disturbed habitats.

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This would mean that Brazil’s most common species are non-endemic generalists but in the other three countries, endemics can be generalists. The only thing I can think is that the isolation of the other three mean that generalists can have large ranges and be common and still be endemic whereas Brazil’s generalists are likely to cross its borders.

I am completely aware that countries are not biogeographically meaningful, but they are areas with values attached nonetheless, and the data are unexpected.

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You’re comparing islands (australia, madagascar) to a single country in the Amazon rainforest; these aren’t equivalent.

A better comparison would probably be to the entire Amazon, but I’m not familiar enough with the biogeography to say for sure - that said like, you have to look at the entire biome not the political boundaries.

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I agree with points made by @charlie and @sopacexplorer

In Australia and Madagascar as islands, the political and meaningful biological boundaries (ie, the land surrounded by ocean) as largely congruous. In Brazil, this isn’t the case, as species which are Amazon endemics will be found n Brazil and many of its neighboring countries.

In Oz and Madagascar, even the subset of common species found close to people’s homes (likely generalists or urban tolerant species) are more likely to still be endemics due to the issue above. In Brazil, these species are likely to be the ones that are found in other cities/suburbs in South America (and thus not be endemics). Most endemics will be in the rare habitats (Amazon, Mata Atlantica, etc.) where human density (and thus density of observations) is lower.

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I just want to clarify and say that people seem to be missing my point a bit. Regardless of whether Brazil is meaningful area or if it is isolated or not, the issue was that it has high (56%) endemism rate which is not reflected in the most observed species, even though the rates are reflected in the other countries. However, my question does seem to have been answered. Thanks!

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Keep in mind, iNaturalist observations aren’t an unbiased sample, so you might also be comparing slightly different things between countries. How many observers are active, what organisms they like to photograph, how easy the endemics are to get to/recognize, how many taxon specialists are involved in identifications, and how well documented the local flora is (like, are there good ID guides/keys easily available?) are all going to play a role in what you see posted on iNaturalist.

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Exactly!! In the entire country of Brazil, there are only about 1,750,000 observations. In California alone, there are 12,650,000. iNaturalist has many uses, but above all it tracks people, and you are never going to get an accurate picture of an ecosystem just through iNat observations, especially outside the US where usage is lower (about half of all iNat obs are just in the US).

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Remember that Brazil is not just the Amazon. It is the country that has most of the Atlantic Forest (20,000 plant species, with 40% endemism, although some biome endemics are shared with Argentina and Paraguay), the entirety of the Caatinga biome, as well as another biodiversity hotspot, the Cerrado (10-12,000 plant species, 35% endemic). As others have said, the endemics are not the most widely observed or easily identified species. The great majority of iNaturalist observers in Brazil observe in urban areas and often record non-native species. There are likely many Brazilian endemics photographed on iNat that have not been identified yet, and also many more that are yet to be recorded. There are likely also endemics observed that have not been marked as endemic on iNat.

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Some also waiting patiently in the Needs ID and Unknown queues.
I have flagged for curation, many missing species for Africa.

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Also, the rate for observations waiting to got to RG is really high in some of those South American countries. I don’t know for Brazil specifically, but for the neighbour Colombia it is about 30% RG only. There are just so many species and so few experts that feel confident enough to determine an observation has to be a single species and not something else (maybe even undescribed)… Especially when it comes to observations from more remote region, where probably most endemics can be found.

I also support the idea that filtering for most observed is probably not of great value when comparing island habitats to a mainland country… with most observed species being likely crossing inland borders

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This is actually a really good point. I was just watching a video yesterday that was basically an interview of Tom Croat at the Missouri Botanical Garden discussing their Aroid collection, and the gist of it was that basically that entire area is so lush and stuff is soooo heavily endemic to small areas that you can cross a small river or go to the next hill and end up with entirely different species. A lot of stuff may honestly be undescribed species.

EDIT: (in case anyone is interested in listening to an absolute expert in his field ramble on for hours about tropical plants, here you go - https://www.youtube.com/watch?v=bCUTbI6h3jA . its two parter, its like three hours worth of video XD)

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I didn’t check whether iNat marked as endemic though. I didn’t find a single Brazilian species with that marker (including the ones that were endemic) and most endemic species for all countries on the site don’t have the marker either. I did my own research to determine whether it was endemic. iNat also marks endemic species as “native” if they have been introduced to other countries, which I don’t see as correct.

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every time you see an introduced, native or endemic tag on a species on iNat, it has been manually added by someone, this isn’t something that occurs automatically

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I would have though so. That’s why so few are marked.

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“Native” tells where the organism evolved. Nothing else. Many plants native to Europe, for example, are introduced to other continents. They’re still native in Europe. They’re not native to, for example, North America. So I don’t see the problem, but perhaps I misunderstood what you wrote.

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I’m at least casually into botany, but I tend to think of plant groups that are characteristic of places, rather than individual species. So Australia has eucalyptuses and true acacias (as opposed to Vachellia), South Africa has proteas and all those funky living rock plants (Lithops et al.), etc. When I think of Brazilian plants, the first things that come to mind are all the plants with extra-floral nectaries in the cerrado and caatinga, the hyperdominant tree species and “species swarms” of the Amazon, and Victoria water lilies. The first two are functional groups rather than taxonomic ones, although as people have mentioned, a number of the cerrado and caatinga plants are endemic. The “species swarms” are, almost by definition, extremely difficult to ID to species. Victoria water lilies (specifically V. amazonica) are found in Brazil…and Guyana.

It’s worth noting that of the top hyperdominant tree species in this paper, the only ones with more than a handful of observations on iNat are the edible palm species, including 2 acai species. Some of these species are endemic to the Amazon, but others occur more widely in South and/or Central America. If a group of plants that are defined by being ridiculously common are under-represented and/or underidentified on iNat, it’s not surprising to me that plants that are rarer and/or have smaller ranges aren’t showing up easily on here

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This topic cannot be proven nor disproved easily due to the sheer number of species out there in the regions under comparison. The Amazon river system spans several countries. I’ve kept some tropical fishes originated from the Amazons. Those fishes may not come from Brazil. It may be Peru or other countries. Like for example Peacock bass. Populations of these fishes look the same to me, but scientists may separate them into species. If a particular population is in brazil exclusively and is named a species instead of a subspecies, that will give an impression there is endemism. We see examples in Arrow frogs, orchids, bromeliads. Some plants and creatures evolve to be slightly different due to isolation by physical barriers such as rivers or mountains, deserts.
How is endemism rate calculated ? I guess it is based on some assumptions. I think I’m not going to do those maths. Island endemism appears to be true. Isolation in the Amazons is likely, as rivers can have oxbow lakes. and there are semi arid almost desert regions in Brazil. However, bigger Islands such as Madagascar or Borneo may have a bigger number of unqiue species. In modern times, species may have reached various continents bypassing the isolation formed by oceans.