''Apodemia mormo'' (Mormon metalmark) is a principally
Nearctic
The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface.
The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America t ...
butterfly in the family
Riodinidae
Riodinidae is the family of metalmark butterflies. The common name "metalmarks" refers to the small, metallic-looking spots commonly found on their wings. The 1532 species are placed in 146 genera. Although mostly Neotropical in distribution, t ...
. It is a particularly fascinating species for ecological and evolutionary research, as evidenced by its shifting
taxonomic
Taxonomy is the practice and science of categorization or classification.
A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
classifications. Conflicting observations of host plants utilized, distinctive morphologies, and a wide range of occupied habitats have prompted investigation into several potential subspecies.
To date, two
genetic studies have been done on ''A. mormo'', with analysis revealing that disjunct populations are genetically and
phenotypically
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...
distinct. These studies support a potential need for refined taxonomies, although a larger body of data is required to make clear decisions.
Populations of ''A. mormo'' are widely distributed throughout western North America, with peripheral colonies located in
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
and
Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
. The Canadian populations have historically lacked scientific study, prompting a series of investigations in the past decade. ''A. mormo'' is the only representative of the family ''Riodinidae'', a primarily
Neotropic
The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone.
Definition
In bioge ...
family consisting of roughly 1500 species, that lives in Canada.
Three populations of ''A. mormo'' have been given conservation statuses: the
Saskatchewan
Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...
population is listed as threatened, while both the
British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
and Comstock Lange populations are classified as endangered.
Conservation
Conservation is the preservation or efficient use of resources, or the conservation of various quantities under physical laws.
Conservation may also refer to:
Environment and natural resources
* Nature conservation, the protection and manageme ...
efforts are complicated by a dependency on human activity for habitat success. Soil disturbances, caused by human and railway traffic, are critical for the survival of host plants and subsequent ''A. mormo'' populations; however, overbearing human presence can lead to habitat destruction. Conservation statuses have been repeatedly defended by research, and recovery strategies developed in response.
Geographic range
''Apodemia mormo'' constitutes the widest ranging North American species of the family ''Riodinidae.'' Populations of ''A. mormo'' span western North America, ranging from Sinola, Mexico to Southwestern Canada, and are found west of
North Dakota
North Dakota () is a U.S. state in the Upper Midwest, named after the Native Americans in the United States, indigenous Dakota people, Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north a ...
primarily in
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
,
Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
,
Arizona
Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
,
New Mexico
)
, population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano)
, seat = Santa Fe
, LargestCity = Albuquerque
, LargestMetro = Tiguex
, OfficialLang = None
, Languages = English, Spanish ( New Mexican), Navajo, Ker ...
, and
Washington
Washington commonly refers to:
* Washington (state), United States
* Washington, D.C., the capital of the United States
** A metonym for the federal government of the United States
** Washington metropolitan area, the metropolitan area centered on ...
. While there are several populations recognized in the US, only two are present in Canada: the British Columbia population, along the Similkameen River Valley, and the Saskatchewan population, in the
Grasslands National Park
Grasslands National Park (French: ') is a Canadian national park located near the village of Val Marie, Saskatchewan, and one of 44 national parks and park reserves in Canada's national park system (though one of only two in Saskatchewan its ...
. The Canadian populations are listed with conservation statuses of “endangered” and “threatened”, respectively.
Rather than a continuous distribution, ''A. mormo'' colonies occur in semi-isolated patches. Population studies have found that small amounts of geographic distance between colonies (15–20 km) are significant to hinder
gene flow
In population genetics, gene flow (also known as gene migration or geneflow and allele flow) is the transfer of genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent a ...
, and render populations phenotypically distinct.
Thus, there is great within species variation depending on geographic location, and taxonomic distinctions are still in flux.
Habitat
Populations of ''Apodemia mormo'' primarily occupy dry, arid habitats that support a high density of their larval host plant: various species of buckwheat (''
Eriogonum
''Eriogonum'' is a genus of flowering plants in the family Polygonaceae. The genus is found in North America and is known as wild buckwheat. This is a highly species-rich genus, and indications are that active speciation is continuing. It in ...
). ''Since ''A. mormo'' is singularly dependent on ''Eriogonum'' during the larval stage, its presence is the most stable predictor of habitat.'' ''
Dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, f ...
s, sloping hillsides,
grassland
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...
s and gravelly
desert
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
s have all been observed as viable environments for ''A. mormo'' habitats, indicating the species’ broad adaptability. Wick investigated
microhabitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
characteristics associated with ''A. mormo'' inhabitance, and found “host plant habitat
with lower elevation, a southerly to southwesterly aspect, lower available soil nitrogen, a steeper slope, higher % bare ground, and higher soil pH”
were most often correlated with presence of ''A. mormo''.
The exact variety of buckwheat which functions as the larval host plant changes with the population being studied. ''E. paucifllorum'', commonly known as the branched umbrella plant, is closely associated with the Saskatchewan population. In British Columbia, ''
Eriogonum niveum
''Eriogonum niveum'' is a species of flowering plant in the buckwheat family known by the common name snow buckwheat. It is native to the Pacific Northwest of North America, where it occurs in British Columbia, Washington, Oregon, and Idaho. '' functions as the larval host plant, while in the population of ''A. m. langei'', ''
Eriogonum nudum
''Eriogonum nudum'' is a perennial shrub of the wild buckwheat genus which is known by the common name naked buckwheat or nude buckwheat.
Description
The ''Eriogonum nudum'' plant is a tall, bare, leafless stem, bifurcating into more stems, ...
'' serves as the primary host and food source.
''A. mormo'' colonies have additionally been correlated with the presence of several other plants. In the Saskatchewan population, presence of
''Ericamerica nauseosa'' (rabbitbrush) is a good predictor of ''A. mormo'' presence, and functions as a secondary nectar source. Furthermore, Wick investigated the possibility of complex dependencies with other observed habitat plants, including “creeping juniper, yellow umbrella plant, saltbush, prickly pear cactus, Colorado rubberweed, yellow sweet clover, wild rose and sage”.
Some level of human interaction with ''A. mormo'' habitats is thought to be crucial for their success. In the Canadian populations, specifically, human railway traffic through habitat corridors provides frequent disturbances to the soil, nurturing the growth of their larval host plant. To similar effect, steep and unstable slopes prone to frequent erosion provide appropriate conditions for host plant prosperity. ''A. mormo'' are rarely found on undisturbed flats.
Food resources
Caterpillars
![Mormon Metalmark (Apodemia mormo)2](https://upload.wikimedia.org/wikipedia/commons/c/c4/Mormon_Metalmark_%28Apodemia_mormo%292.jpg)
In general, species of ''Eriogonum'' serve as larval host plants for ''A. mormo''. In the Saskatchewan population, ''Eriogonum niveum'', or snow buckwheat, functions as the primary host plant and food resource. In the British Columbia population, the branched umbrella plant ''Eriogonum pauciflorum'' solely fulfills this role.
These species flourish with adequate soil disturbances, thus only those on rocky hillsides tend to bloom and attract ''A. mormo''.
Adults
''Eriogonum pauciflorum'' doubles as the primary nectar source for adult Mormon Metalmarks; however, rabbitbrush (''Ericameria nauseosus'') is often used as a secondary nectar source.
''A. mormo'' preferentially visit branched umbrella plants, and have only been observed visiting rabbitbrush once ''Eriogonum pauciflorum'' flowers are in decay.
Oviposition
Differing observations have been made regarding the oviposition behavior of ''Apodemia mormo''. In California, Powell reports ''A. m. langei'' ovipositing on deteriorating, lower leaves of the ''Eriogonum'', typically in groups of 2-4 eggs.
However, in the Canadian populations, Wick observes entirely different behavior. The specimens of ''A. mormo'' were seen laying eggs near their host plants, but not directly on the leaves. Instead, females oviposited a single egg in rocky crevices or soil cracks. This occurred in the afternoon, with a duration of up to 30 seconds.
[Wick, Ashley Anne, et al. "First observations of Mormon Metalmark (Apodemia mormo) oviposition behaviour in Canada." ''The Canadian Field-Naturalist'' 126.1 (2012): 34-37.] Temperature differentials between Southern California and Canada may help to explain these observed differences. Since exposure to sunlight supports increased survival in cold habitats, laying eggs on exposed rocky surfaces could be an adaptive advantage in the Canadian populations.
Regardless, these populations still require ovipositing nearby suitably mature host plants, since the larvae will require adequate protection and nutrients once hatched.
Life cycle
Egg
Eggs are laid by adult females in clusters ranging from 1-4, depending on the specific population being observed. In Canadian populations, Scott reported the eggs as resembling “flattened spheres”, and described their color as “pink turning purple”.
[Scott, J.A. 1986. The butterflies of North America: A natural history and field guide. Stanford University Press, Stanford. 581 pp.] In contrast, Wick observed “amber coloured” eggs the size of a “pinhead” in the Saskatchewan population. Egg development is potentially dependent on habitat choice, temperature, and exposure to solar radiation; further studies are needed in regards to ''A. mormo''.
Caterpillar
Larvae emerge from eggs during the winter, and are thought to remain at a single host plant during this stage of their lives. Early instar larvae hibernate following their eclosion. From June to July, the late instar larvae feed nocturnally on the leaves of their host plants, which are various species of buckwheat, depending on the population under study. During the day, larvae can be found resting in nests made of leaf debris and silk at the base of the plant.
Pupa
Pupation takes place by between July and August, with “hairy…mottled brown” pupas congregated in leaf litter underneath the host plant.
Adult
Adult emergence occurs spread out over the course of a month, with males preceding females by a few days. These mature butterflies live between nine and twelve days, with females having a slightly longer lifespan than males. During this time, ''A. mormo'' prefer to stay near to their host plant, travelling short distances of up to 50 m. Again, there is a slight distinction between sexes, with females tending to fly farther than males. Both males and females forage for nectar.
Reproduction
Mating occurs approximately three days into the adult lifespan. Females seek out male partners, who wait on food plants for their arrival. It has been postulated that females of the subspecies ''Langei'' mate multiply, because of an observed ratio of 2.6 spermatophores per female.
Enemies
Parasites
''Trichogramma kaykai,'' a small parasitic wasp, parasitize ''Apodemia mormo deserti'', primarily located in the Mojave Desert. These wasps lay clutches of 3-5 offspring in each ''Apodemia mormo deserti'' egg.
Genetics
Population genetics
The proper taxonomic classifications for ''Apodemia mormo'' are still under debate. Because the species tends to occur in small, isolated populations, the relatedness between populations is frequently questioned. A population genetics study conducted by Proshek revealed that the British Columbia and Saskatchewan populations of ''A. mormo'' in Canada are genetically distinct; furthermore, they uncovered higher genetic diversity in eastern vs. western populations, emphasizing low diversity in the British Columbia population.
A second genetic study using AFLPs supports low genetic diversity in the British Columbia population, and reports high spatial genetic structure and limited gene flow between populations.
Furthermore, they found genetic similarities between the Saskatchewan population and more eastern populations. The combined results of these two studies indicate potentials for current migration activities, as well as high
genetic drift
Genetic drift, also known as allelic drift or the Wright effect, is the change in the frequency of an existing gene variant (allele) in a population due to random chance.
Genetic drift may cause gene variants to disappear completely and there ...
.
In addition to genetic evidence, morphological and behavioral data are required to make firm taxonomic distinctions; however, genetic investigation has begun to reveal some of the challenges of classification.
Subspecies
There are at least twenty named subspecies of ''A. mormo.''
Below is a partial list of recognized subspecies:
# ''
A. m. langei''
# ''A. m. pueblo' ''
# ''A. m. mejicanus''
# ''A. m. nigrescens''
# ''A. m. arenaria''
# ''A. m. pratti''
Physiology
''A. mormo'' populations exhibit significant morphological variation, and therefore no singular description is a perfect fit for the species. In general, the butterfly has a wingspan of 25–35 mm, with males being slightly smaller than females. Females are further differentiated from males by their number of functional legs; females possess three pairs, while males do not utilize their shortened forelegs and thus only have two. The Canadian populations have been described as having white checked dark brown wings, a gray body, green eyes, and black and white banded antennae. There is a reddish tint towards the base of the forewings, and the ventral side of the wings are gray.
Flight
Both the Canadian populations and the endangered ''A. m. langei'' are
univoltine
Voltinism is a term used in biology to indicate the number of broods or generations of an organism in a year. The term is most often applied to insects, and is particularly in use in sericulture, where silkworm varieties vary in their voltinism.
...
, meaning they have one generation annually. Following emergence, ''A. mormo'' adults have a flight period of roughly thirty days, with specific timing ranging from mid-July into September.
They reach their highest concentration two weeks after the first adult emerges, usually during August. Adults do not fly long distances, and display mostly sedentary behaviors. The primary purposes for flight include foraging for nectar on nearby plants, and seeking out mates. Their flight pattern can be characterized as short, linear and fast.
Conservation
Status
Low genetic diversity, small, distinctive populations, semi-isolated geographic distribution, and habitat dependence all predispose ''A. mormo'' to risk of extinction and warrant conservation efforts. In particular, Canadian populations are perceived as especially vulnerable to stochastic events, such as natural disasters, climate change, and outbreaks of disease. Conservation efforts have been in effect for the Canadian populations since the early 2000s under COSEWIC,
and for ''A. m. langei'' since 1976 under the US Federal Endangered Species Act.
Habitat loss
A key concern for conservationists is potential
habitat loss
Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
. Urban development,
agricultural expansion
Agricultural expansion describes the growth of agricultural land (arable land, pastures, etc.) especially in the 20th and 21st centuries.
The agricultural expansion is often explained as a direct consequence of the global increase in food and ene ...
, ranching practices, and campground activities may be responsible for disturbing natural habitats and breaking them up into small patches. While efforts to prevent such fragmentation are encouraged, Crawford emphasizes a need to conserve even small habitat zones, which may function as bridges between sub-populations.
[Pruss, S. D., et al. "Recovery strategy for the Mormon Metalmark (Apodemia mormo) Prairie population." ''Canada species at risk act. Recovery strategy series, parks Canada agency, Ottawa''(2008).] Furthermore, habitat loss might result from invasive, competitive plant species. ''A. mormo'' populations would severely suffer if these intruders successfully outcompete local ''Eriogonum'' species, given their dependency on the host plant.
[Keeler, M. S., F. S. C. Chew, B. C. Goodale and J. M. Reed. 2006. Modelling the impacts of two exotic invasive species on a native butterfly: top-down vs. bottom-up effects. Journal of Animal Ecology 75: 777-788.] Finally, ''Eriogonum'' plants go into senescence after 10–15 years. This poses a significant problem for habitat maintenance, and suggests a need for regular dispersal of new ''Eriogonum'' plants as part of conservation efforts.
Recovery strategies
Recovery strategies are consistently developed and updated as new research emerges. Regarding the Lange population in California, efforts to clear weedy vegetation and recreate mounds of sand and soil were started in 1991. ''Eriogonum'' species were seeded through the habitats and the land was completely fenced in, preventing destructive human presence.
With respect to the Canadian populations, Crawford suggests the development of strategies which recover habitat patches, regardless of size, and encourage gene flow between isolated populations.
References
External links
Mormon metalmark Butterflies and Moths of North America
Mormon metalmark Butterflies of Canada
{{Taxonbar, from=Q1380884
Apodemia
Butterflies of North America
Taxa named by Baron Cajetan von Felder
Taxa named by Rudolf Felder
Butterflies described in 1859