Notes from the Field: Cliff racer

Scientific name

Cinis descendens

Meaning: Cinis: from [ash] in Latin; descendens from [descends] in Latin.

Translation: descending from the ash; describes hunting behaviour in ash mountains of Vvardenfell.

Common name

Cliff racer

cliff racer
A cliff racer hovering above a precipice on Vvardenfell.

Taxonomic status

Kingdom Animalia; Phylum Chordata; Class Aves; Subclass Archaeornithes; Family Vvardidae; Genus Cinis; Species descendens

Conservation status

Least Concern [circa 3E 427]

Threatened [circa 4E 433]

Distribution

Once widespread throughout the north eastern region of Tamriel, occupying regions from the island of Vvardenfell to mainland Morrowind and Solstheim. Despite their name, the cliff racer is found across nearly all geographic regions of Vvardenfell, although the species is found in greatest densities in the rocky interior region of Stonefalls.

Following a purge of the species as part of pest control management, the cliff racer was effectively exterminated from parts of its range, including local extinction on the island of Solstheim. Since the cull the cliff racer is much less abundant throughout its range although still distributed throughout much of Vvardenfell and mainland Morrowind.

Morrowind
The province of Morrowind, which largely contains the distribution of the cliff racer. The island of Solstheim is found to the northwest of the map (the lower half of the island can be seen in brown).

Habitat

Although, much as the name suggests, the cliff racer prefers rocky outcroppings and mountainous regions in which it can build its nest, the species is frequently seen in lowland swamp and plains regions of Morrowind.

Behaviour and ecology

The cliff racer is a highly aggressive ambush predator, using height and range to descend on unsuspecting victims and lashing at them with its long, sharp tail. Although preferring to predate on small rodents and insects (such as kwama), cliff racers have been known to attack much larger beasts such as agouti and guar if provoked or desperate. The highly territorial nature of cliff racer means that they often attack travellers, even if they pose no immediate threat or have done nothing to provoke the animal.

Cliff_Racer_(Online).png
A cliff racer descends upon its prey.

Despite the territoriality of cliff racers, large flocks of them can often be found in the higher altitude regions of Vvardenfell, perhaps facilitated by an abundance of food (reducing competition) or communal breeding grounds. Attempts by researchers to study these aggregations have been limited due to constant attacks and damage to equipment by the flock.

Demography

Prior to the purging of cliff racers in the early 4E by Saint Jiub, the cliff racer was overly abundant throughout its range and considered a pest species by native peoples. Although formal studies on the population structure of the species was never conducted due to their aggressive nature, suppositions of migratory rates, distances and geographies suggested that potentially three major (ESUs) populations existed; one of Solstheim, one of Vvardenfell, and another of mainland Morrowind.

Following the control measures implemented, the population size of these populations of cliff racers declined severely; however, given the survival of the majority of the population it does not appear this bottleneck has severely impacted the longevity of the species. The extirpation of the Solstheim population of cliff racers likely removed a unique ESU from the species, given the relative isolation of the island. Whether the island will be recolonised in time by Vvardenfell cliff racers is unknown, although the presence of any cliff racers back onto Solstheim would likely be met with strong opposition from the local peoples.

Adaptive traits

The broad wings, dorsal sail and long tail allow the cliff racer to travel large distances in the air, serving them well in hunting behaviour. The drawback of this is that, if hunting during the middle hours of the day, the cliff racer leaves an imposing shadow on the ground and silhouette in the sky, often alerting aware prey to their presence. That said, the speed of descent and disorienting cry of the animal often startles prey long enough for the cliff racer to attack.

The plumes of the cliff racer are a well-sought-after commodity by local peoples, used in the creation of garments and household items. Whether these plumes serve any adaptive purpose (such as sexual selection through mate signalling) is unknown, given the difficulties with studying wild cliff racer behaviour.

Management actions

Although suffering from a strong population bottleneck after the purge, the cliff racer is still relatively abundant across much of its range and maintains somewhat stable size. Management and population control of the cliff racer is necessary across the full distribution of the species to prevent strong recovery and maintain public safety and ecosystem balance. Breeding or rescuing cliff racers is strictly forbidden and the species has been widely declared as ‘native pest’, despite the somewhat oxymoron nature of the phrase.

“Who Do You Think You Are?”: studying the evolutionary history of species

The constancy of evolution

Evolution is a constant, endless force which seeks to push and shape species based on the context of their environment: sometimes rapidly, sometimes much more gradually. Although we often think of discrete points of evolution (when one species becomes two, when a particular trait evolves), it is nevertheless a continual force that influences changes in species. These changes are often difficult to ‘unevolve’ and have a certain ‘evolutionary inertia’ to them; because of these factors, it’s often critical to understand how a history of evolution has generated the organisms we see today.

What do I mean when I say evolutionary history? Well, the term is fairly diverse and can relate to the evolution of particular traits or types of traits, or the genetic variation and changes related to these changes. The types of questions and points of interest of evolutionary history can depend at which end of the timescale we look at: recent evolutionary histories, and the genetics related to them, will tell us different information to very ancient evolutionary histories. Let’s hop into our symbolic DeLorean and take a look back in time, shall we?

Labelled_evolhistory
A timeslice of evolutionary history (a pseudo-phylogenetic tree, I guess?), going from more recent history (bottom left) to deeper history (top right). Each region denoted in the tree represents the generally area of focus for each of the following blog headings. 1: Recent evolutionary history might look at individual pedigrees, or comparing populations of a single species. 2: Slightly older comparisons might focus on how species have arisen, and the factors that drive this (part of ‘phylogeography’). 3: Deep history might focus on the origin of whole groups of organisms and a focus on the evolution of particular traits like venom or sociality.

Very recent evolutionary history: pedigrees and populations

While we might ordinarily consider ‘evolutionary history’ to refer to events that happened thousands or millions of years ago, it can still be informative to look at history just a few generations ago. This often involves looking at pedigrees, such as in breeding programs, and trying to see how very short term and rapid evolution may have occurred; this can even include investigating how a particular breeding program might accidentally be causing the species to evolve to adapt to captivity! Rarely does this get referred to as true evolutionary history, but it fits on the spectrum, so I’m going to count it. We might also look at how current populations are evolving differently to one another, to try and predict how they’ll evolve into the future (and thus determine which ones are most at risk, which ones have critically important genetic diversity, and the overall survivability of the total species). This is the basis of ‘evolutionarily significant units’ or ESUs which we previously discussed on The G-CAT.

Captivefishcomic
Maybe goldfish evolved 3 second memory to adapt to the sheer boringness of captivity? …I’m joking, of course: the memory thing is a myth and adaptation works over generations, not a lifetime.

A little further back: phylogeography and species

A little further back, we might start to look at how different populations have formed or changed in semi-recent history (usually looking at the effect of human impacts: we’re really good at screwing things up I’m sorry to say). This can include looking at how populations have (or have not) adapted to new pressures, how stable populations have been over time, or whether new populations are being ‘made’ by recent barriers. At this level of populations and some (or incipient) species, we can find the field of ‘phylogeography’, which involves the study of how historic climate and geography have shaped the evolution of species or caused new species to evolve.

Evolution of salinity
An example of trait-based phylogenetics, looking at the biogeographic patterns and evolution/migration to freshwater in perch-like fishes, by Chen et al. (2014). The phylogeny shows that a group of fishes adapted to freshwater environments (black) from a (likely) saltwater ancestor (white), with euryhaline tolerance evolving two separate times (grey).

One high profile example of phylogeographic studies is the ‘Out of Africa’ hypothesis and debate for the origination of the modern human species. Although there has been no shortage of debate about the origin of modern humans, as well as the fate of our fellow Neanderthals and Denisovans, the ‘Out of Africa’ hypothesis still appears to be the most supported scenario.

human phylogeo
A generalised diagram of the ‘Out of Africa’ hypothesis of human migration, from Oppenheimer, 2012. 

Phylogeography is also component for determining and understanding ‘biodiversity hotspots’; that is, regions which have generated high levels of species diversity and contain many endemic species and populations, such as tropical hotspots or remote temperate regions. These are naturally of very high conservation value and contribute a huge amount to Earth’s biodiversity, ecological functions and potential for us to study evolution in action.

Deep, deep history: phylogenetics and the origin of species (groups)

Even further back, we start to delve into the more traditional concept of evolutionary history. We start to look at how species have formed; what factors caused them to become new species, how stable the new species are, and what are the genetic components underlying the change. This subfield of evolution is called ‘phylogenetics’, and relates to understanding how species or groups of species have evolved and are related to one another.

Sometimes, this includes trying to look at how particular diagnostic traits have evolved in a certain group, like venom within snakes or eusocial groups in bees. Phylogenetic methods are even used to try and predict which species of plants might create compounds which are medically valuable (like aspirin)! Similarly, we can try and predict how invasive a pest species may be based on their phylogenetic (how closely related the species are) and physiological traits in order to safeguard against groups of organisms that are likely to run rampant in new environments. It’s important to understand how and why these traits have evolved to get a good understanding of exactly how the diversity of life on Earth came about.

evolution of venom
An example of looking at trait evolution with phylogenetics, focusing on the evolution of venom in snakes, from Reyes-Velasco et al. (2014). The size of the boxes demonstrates the number of species in each group, with the colours reflecting the number of venomous (red) vs. non-venomous (grey) species. The red dot shows the likely origin of venom.

Phylogenetics also allows us to determine which species are the most ‘evolutionarily unique’; all the special little creatures of plant Earth which represent their own unique types of species, such as the tuatara or the platypus. Naturally, understanding exactly how precious and unique these species are suggests we should focus our conservation attention and particularly conserve them, since there’s nothing else in the world that even comes close!

Who cares what happened in the past right? Well, I do, and you should too! Evolution forms an important component of any conservation management plan, since we obviously want to make sure our species can survive into the future (i.e. adapt to new stressors). Trying to maintain the most ‘evolvable’ groups, particularly within breeding programs, can often be difficult when we have to balance inbreeding depression (not having enough genetic diversity) with outbreeding depression (obscuring good genetic diversity by adding bad genetic diversity into the gene pool). Often, we can best avoid these by identifying which populations are evolutionarily different to one another (see ESUs) and using that as a basis, since outbreeding vs. inbreeding depression can be very difficult to measure. This all goes back to the concept of ‘adaptive potential’ that we’ve discussed a few times before.

In any case, a keen understanding of the evolutionary trajectory of a species is a crucial component for conservation management and to figure out the processes and outcomes of evolution in the real world. Thus, evolutionary history remains a key area of research for both conservation and evolution-related studies.

 

“How do you conserve genes?”: clarifying conservation genetics

Sometimes when I talk about the concept of conservation genetics to friends and family outside of the field, there can be some confusion about what this actually means. Usually, it’s assumed that means the conservation of genetics: that is, instead of trying to conserve individual animals or plants, we try to conserve specific genes. While in some cases this is partially true (there might be genes of particular interest that we want to maintain in a wild population), often what we actually mean is using genetic information to inform conservation management and to give us the best chance of long-term rescue for endangered species.

DNA Zoo comic
Don’t worry, it’s an open range zoo: the genes have plenty of room to roam.

See, the DNA of individuals contains much more information than just the genes that make up an organism. By looking at the number, frequency or distribution of changes and differences in DNA across individuals, populations or species, we can see a variety of different patterns. Typically, genetics-based conservation analysis is based on a single unifying concept: that different forces create different patterns in the genetic make-up of species and populations, and that these can be statistically evaluated using genetic data. The exact type or scale of effect depends on how the data is collected and what analysis we use to evaluate that data, although we could do multiple types of analysis using the same dataset.

Oftentimes, we want to know about the current or historical state of a species or population to best understand how to move forward: by understanding where a species has come from, what it has been affected by, and how it has responded to different pressures, we can start to suggest and best manage these species into the future.

However, there are lots of possible avenues for exploration: here are just a few…

Evolutionary significant units (ESUs) and management units (MUs)

One commonly used application of genetic information for conservation is the designation of what we call ‘Evolutionary Significant Units’ (ESUs). Using genetics, we can determine the boundaries of particular populations which correspond to their own unique evolutionary groups. These are often the results of historical processes which have separated and driven the independent evolution of each ESU, usually with low or no gene flow across these units. Generally, managing and conserving each of these can lead to overall more robust management of the species as a whole by making sure certain groups that have unique and potentially critical adaptations are maintained in the wild. Although ESUs can sometimes be arguable (particularly when there is some, but not much, gene flow across units), it forms an important aspect of conservation designations.

In cases of shorter term separations across these populations, where there are noticeable differences in the genetics of the populations but not necessarily massively different evolutionary histories, conservationists will sometimes refer to ‘Management Units’ (MUs). These have much weaker evolutionary pressure behind them but might be indicative of very recent impacts, such as human-driven fragmentation of habitat or contemporary climate change. MUs often reflect very sudden and recent changes in populations and might have profound implications for the future of these groups: thus, they are an important way of assessing the current state of the species. The next couple of figures demonstrate this from one of my colleagues’ research papers.

YPP_map
The geographic distributions of Yarra pygmy perch populations, generously taken from Brauer et al. (2013). Each dot and number on the map represents a single population of pygmy perch used in the analysis. The colour of the population represents which MU it belongs to, whilst the shape of the marker represents the ESU. To make this easier to visualise, the solid lines indicate the boundaries of ESUs while the dashed lines represent MU boundaries. You’ll notice that MUs are subsets of ESUs, and that Population 6 actually fits into two different ESUs: see below.
YPP_Structure
An example of the output of an analysis (STRUCTURE) that determines population boundaries for Yarra pygmy perch using genetic data, generously taken from Brauer et al. (2013). Structure is an ‘assignment test’; using the input genetic information, it tries to make groups of individuals which are more similar to one another than other groups. In the graphs, each small column represents a single individual, with the colour bars representing how well it fits that (colour) population. The smaller numbers at the bottom and the labels above the graphs represent geographic populations (see the figure above). A) Shows the 4 major ESUs of Yarra pygmy perch, with some clear mixing between the Eastern ESU and the Merri/Curdies ESU in population 6. The rest of the populations fit pretty well entirely into one ESU. B) The MUs of Yarra pygmy perch, which shows the genetic structure within ESUs that can’t be seen well in A). Notice that some ESUs are made of many MUs (E.g. Central) while others are only one MU (e.g. MDB).

The two can be thought of as part of the same hierarchy, with ESUs reflecting more historic, evolutionary groups and MUs reflecting more recent (but not necessarily evolutionary) groups. For conservation management, this has traditionally meant that individuals from one ESU were managed independent of one another (to preserve their ‘pure’ evolutionary history) whilst translocations of individuals across MUs were common and often recommended. This is based on the idea that mixing very genetically different populations could cause adaptive genes in each population to become ‘diluted’, negatively affecting the ability of the populations to evolve: this is referred to as ‘outbreeding depression’ (OD).

Coffee comic
Sometimes, adding something can make what you had even worse than before. The most depressing analogy of outbreeding depression; a ruined coffee.

However, more recent research has suggested that the concerns with OD from mixing across ESUs are less problematic than previously thought. Analysis of the effect of OD versus not supplementing populations with more genetic diversity has shown that OD is not the more dangerous option, and there is a current paradigm push to acknowledge the importance of mixing ESUs where needed.

Adaptive potential and future evolution

Understanding the genetic basis of evolution also forms an important research area for conservation management. This is particularly relevant for ‘adaptive potential’: that is, the ability for a particular species or population to be able to adapt to a variety of future stressors based on their current state. It is generally understood that having lots of different variants (alleles) of genes in the total population or species is a critical part of evolution: the more variants there are, the more choices there are for natural selection to act upon.

We can estimate this from the amount of genetic diversity within the population, as well as by trying to understand their previous experiences with adaptation and evolution. For example, it is predicted that species which occur in much more climatically variable habitats (such as in desert regions) are more likely to be able to handle and tolerate future climate change scenarios since they’ve demonstrated the ability to adapt to new, more extreme environments before. Examples of this include the Australian rainbowfishes, which are found in pretty well every climatic region across the continent (and therefore must be very good at adapting to new, varying habitats!).

Rainbowfish both.jpg
Left: The distribution of rainbowfish across Australia, with each colour representing a particular ecotypeRight: A photo of a (very big) tropical rainbowfish taken from a recent MELFU field trip. Source: MELFU Facebook page. He really got around after that one stint in that children’s story.

Genetics-based breeding programs and pedigrees

A much more direct use of genetic information for conservation is in designing breeding programs. We know that breeding related individuals can have very bad results for offspring (this is referred to as ‘inbreeding depression’): so obviously, we would avoid breeding siblings together. However, in complex breeding systems (such as polygamous animals), or in wild populations, it can be very difficult to evaluate relationships and overall relatedness.

That’s where genetics comes in: by looking at how similar or different the DNA of two individuals are, we can not only check what relationship they are (e.g. siblings, cousins, or very distantly related) but also get an exact value of their genetic relatedness. Since we know that having a diverse gene pool is critical for future adaptation and survival of a species, genetics-based breeding programs can maximise the amount of genetic diversity in following generations. We can even use a computer algorithm to make the very best of breeding groups, using a quirky program called SWINGER.

Cats DNA dating
If You Are the One, conservation genetics edition.

Taxonomy for conservation legislation

Another (slightly more complicated) application of genetics is the designation of species status. Large amounts of genetic information can often clarify complex issues of species descriptions (later issues of The G-CAT will discuss exactly how this works and why it’s not so straightforward…).

Why should we care what we call a species or not? Well, much of the protective legislation at the government level is designed at the species-level: legislative protections are often designated for a particular species, but doesn’t often distinguish particular populations. Thus, misidentified species can sometimes but lost if they were never detected as a unique species (and assumed to be just a population of another species). Alternatively, managing two species as one based on misidentification could mess with the evolutionary pathways of both by creating unfit hybrid species which do not naturally come into contact together (say, breeding individuals from one species with another because we thought they were the same species).

Cryptic cats comic
Awkward.

Additionally, if we assume that multiple different species are actually only one species, this can provide an overestimate of how well that species is doing. Although in total it might look like there are plenty of individuals of the species around, if this was actually made of 4 separate species then each one would be doing ¼ as well as we thought. This can feed back into endangered status classification and thus conservation management.

 

These are just some of the most common examples of applied genetics in conservation management. No doubt going into the future more innovative and creative methods of applying genetic information to maintaining threatened species and populations will become apparent. It’s an exciting time to be in the field and inspires hope that we may be able to save species before they disappear from the planet permanently.