Unintelligent Design - How Painted Lady Butterflies Migrate Thousands of Miles All For Nothing

Painted Lady, Vanessa cardui

Photo credit: Roger Vila

Painted Lady, Vanessa cardui
div class="credit">Photo credit: Gerard Talavera

Non-stop flight: in a world-first, researchers map a 4,200 km transatlantic flight of the Painted Lady butterfly | About us

Reader with long memories may recall my article from 2011 in which I explained how the annual migration of thousands of painted lady butterflies (Vannesa cardui) from Southern Europe and North Africa into northern Europe made no sense at all from an intelligent design point of view, because not a single one of them or their offspring ever survived even the mildest of European winters.

This, one of the most attractive of butterflies, reaches all parts of the British Isles, in some years migrating as far north as the Orkney and Shetland Island. It is the only butterfly ever recorded in Iceland.

And now a group of scientists have worked out that some painted ladies that turned up on the north coast of South America migrated there across at least 4,200 Km of open Atlantic Ocean in a few days.

The Painted Lady butterfly, scientifically known as Vanessa cardui, is one of the most widespread butterfly species in the world. Here’s a detailed overview of its origins, habitat, and life cycle:

Origins and Distribution

The Painted Lady butterfly is a member of the family Nymphalidae. It is found on every continent except Antarctica and South America. The species is highly migratory, with some populations traveling thousands of miles. This wide distribution and migratory behavior have contributed to its adaptability to various environments.

Appearance

• Wingspan: Approximately 5-9 centimeters (2-3.5 inches).
• Coloration: The upper side of the wings is orange with black and white spots, while the underside is more muted, featuring brown, black, and gray patterns which aid in camouflage.

Habitat

Painted Lady butterflies inhabit diverse environments, including gardens, meadows, fields, and roadsides. They are particularly attracted to areas with abundant nectar-producing flowers.

Life Cycle

The life cycle of the Painted Lady butterfly consists of four main stages: egg, larva (caterpillar), pupa (chrysalis), and adult butterfly.

1. Egg
   • Appearance: Small, greenish-blue, and ribbed.
   • Duration: 3-5 days.
   • Location: Eggs are laid singly on the leaves of host plants, primarily thistles, mallows, and hollyhocks.
2. Larva (Caterpillar)
   • Appearance: Black with yellow stripes and spiny.
   • Duration: 7-14 days.
   • Behavior: The caterpillars are voracious feeders, consuming leaves of host plants. They may create silk nests for protection.
3. Pupa (Chrysalis)
   • Appearance: The chrysalis is mottled brown and green with spiky projections.
   • Duration: 7-10 days.
   • Transformation: Inside the chrysalis, the caterpillar undergoes metamorphosis, transforming into an adult butterfly.
4. Adult Butterfly
   • Emergence: After the metamorphosis is complete, the adult butterfly emerges from the chrysalis.
   • Behavior: Adults are nectar feeders, favoring flowers such as thistles, asters, and buddleia.
   • Lifespan: Adults live for about 2-4 weeks. During this time, they mate and lay eggs, continuing the cycle.

Migration

Painted Lady butterflies are known for their impressive migratory behavior. For example, in North America, they migrate from Mexico and Central America to the northern United States and Canada during the spring and summer. In Europe, they migrate from Africa to northern Europe.

Importance

Painted Lady butterflies play a significant role in pollination. Their widespread presence and migratory nature make them an essential part of many ecosystems. Additionally, they serve as important indicators of environmental health and biodiversity.

Conservation

While the Painted Lady butterfly is not considered endangered, habitat loss and climate change can impact their populations. Conservation efforts focus on preserving their habitats and promoting biodiversity to ensure healthy ecosystems.

Interesting Facts

• The Painted Lady butterfly is sometimes called the "Cosmopolitan" due to its global presence.
• During migration, they can travel at speeds of up to 30 miles per hour.
• They have a unique, erratic flight pattern which helps them avoid predators.

In summary, the Painted Lady butterfly, Vanessa cardui, is a remarkable species with a vast distribution and fascinating life cycle. Its adaptability and migratory behavior make it a subject of interest for scientists and butterfly enthusiasts alike.

Do those which migrate north in summer survive the winter in any form.

Painted Lady butterflies (Vanessa cardui) that migrate north during the summer typically do not survive the winter in their northern habitats in any form. Here's an explanation of their life cycle in the context of seasonal changes and migration:

Migration and Seasonal Survival

Summer Migration

• Northward Migration: Painted Lady butterflies migrate north in the spring and summer from warmer regions, such as Mexico and Central America, to areas in the northern United States, Canada, and parts of Europe.
• Reproduction: During their time in the north, they mate and lay eggs, continuing their life cycle through several generations over the summer.

Winter Survival

• Inability to Overwinter: Painted Lady butterflies cannot survive the harsh winter conditions in their northern habitats. Unlike some butterfly species that can overwinter in certain stages (e.g., as eggs, larvae, pupae, or adults), Painted Ladies do not have this adaptation. They lack the ability to enter diapause (a state of suspended development) that would allow them to withstand freezing temperatures.
• Return Migration: Instead of overwintering, Painted Lady butterflies rely on a return migration to warmer climates. As the weather cools in the autumn, the butterflies begin their southward journey back to regions with milder winters.
• Generational Movement: The migration is usually multi-generational. The butterflies that initially migrated north are not the same individuals that make the return journey. Instead, successive generations continue the migration cycle.

Southern Habitats

• Warmer Regions: In their southern habitats, such as Mexico, Central America, and parts of North Africa, Painted Lady butterflies can continue their life cycle year-round. The warmer climate allows for continuous breeding, feeding, and development.

Summary
Painted Lady butterflies that migrate north in the summer do not survive the winter in their northern habitats. Instead, they depend on a southward migration to warmer regions where their life cycle can continue uninterrupted. This migratory behavior ensures the species' survival despite the seasonal changes in temperature and availability of resources in different parts of the world.

It used to be thought that, unlike many species which over-winter in Northern Europe as hibernating adults, pupae, larvae or eggs, nothing remains of the annual migration of the painted lady and Europe is repopulated each year entirely from the stock that remained in North Africa, however, recent research suggests that some offspring of the migrants migrate south again at the end of summer, back to their parents or grandparents homelands where breeding is continuous the year round, so nothing was gained by the northern migration.

I also used this futility as an example of unintelligent design in my book, The Unintelligent Designer: Refuting the Intelligent Design Hoax (Page 83).

In October 2013, Gerard Talavera, a researcher from the Botanical Institute of Barcelona at CSIC, made a surprising discovery of Painted Lady Butterflies on the Atlantic beaches of French Guiana - on the northern coast of South America. The species is not a South American species and the North American population migrates north to the northern USA and Canda during summer, so the obvious conclusion was that somehow they had made the 7000 Km journey over open water, in a single flight from West Africa or western Europe, lasting probably 6-8 days.

This feat, remarkable though it is, is not unknown in butterflies. Monarch butterflies regularly turn up in Western Europe as vagrants assumed to have become disorientated in tropical storms during their migration northward from Mexico. Enough have made it to southern Spain to have established a colony in Andalucia, where I have seen them on the Mediterranean coast Puerto Benus, west of Malaga.

The discovery of painted lady butterflies in French Guiana sparked an international research programme, led by Gerard Talaverna, which has now reported its findings, open access, in the journal Nature Communications. The team included Tomasz Suchan from the W. Szafer Institute of Botany, and Clément Bataille, associate professor in the Department of Earth and Environmental Sciences at the University of Ottawa - with Megan Reich, a postdoctoral researcher from the Department of Biology at uOttawa, Roger Vila and Eric Toro Delgado, scientists from the Institute of Evolutionary Biology (IBE, CSIC-UPF) and Naomi Pierce, a professor of Biology in the Department of Organismic and Evolutionary Biology at Harvard University The research is explained in a University of Ottawa press release:

Non-stop flight: in a world-first, researchers map a 4,200 km transatlantic flight of the Painted Lady butterfly

This discovery and the use of next-generation molecular techniques and tools open new areas of research in insect migration in the context of climate change.

Highlights

• In a world-first, an international team of scientists demonstrated that Painted Lady butterflies (Vanessa cardui) flew at least 4,200 km over the ocean from West Africa to French Guiana, South America.
• Using novel techniques, among them isotope-based geolocation, they found that the butterflies probably originated in Europe, extending this migratory flight over 7000 km.
• The butterflies made the transatlantic journey in 5 to 8 days, actively flying but aided by favorable trade winds.

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In October 2013, Gerard Talavera, a researcher from the Botanical Institute of Barcelona at CSIC, made a surprising discovery of Painted Lady Butterflies on the Atlantic beaches of French Guiana—a species not typically found in South America. This unusual sighting prompted an international study to investigate the origin of these butterflies.

A Combination of Novel Techniques Solves the Enigma

Using innovative multidisciplinary tools, the research team embarked on a scientific mission to track the journey and origin of those mysterious Painted Ladies.

First, the research team reconstructed wind trajectories for the period preceding the arrival of these butterflies in October 2013. They found exceptionally favorable wind conditions that could support a transatlantic crossing from western Africa, opening the possibility that those individuals might have flown across the entire ocean.

After sequencing the genomes of these individuals and analyzing them in comparison to populations globally, researchers discovered that the butterflies had a closer genetic relatedness to African and European populations. This result eliminated the likelihood of these individuals coming from North America, thereby reinforcing the hypothesis of an oceanic journey.

Researchers leveraged a unique combination of next-generation molecular techniques. They sequenced the DNA of pollen grains carried by these butterflies. They identified two species of plants that only grow in tropical Africa indicating that the butterflies nectared on African flowers before engaging into their transatlantic journey. They analyzed hydrogen and strontium isotopes in the butterflies’ wings, a chemical signal that acts as a “fingerprint” of the region of natal origin. Combining isotopes with a model of habitat suitability for larval growth revealed potential natal origin in western Europe, possibly France, Ireland, the United Kingdom, or Portugal.

Dr. Bataille underlines the methodological novelty of this study:

It is the first time that this combination of molecular techniques including isotope geolocation and pollen metabarcoding is tested on migratory insects. The results are very promising and transferable to many other migratory insect species. The technique should fundamentally transform our understanding of insect migration.

Dr. Clément P. Bataille, co-lead author
Department of Earth and Environmental Sciences
University of Ottawa, Ottawa, ON, Canada.

We usually see butterflies as symbols of the fragility of beauty, but science shows us that they can perform incredible feats. There is still much to discover about their capabilities.

Roger Vila, co-author
Institut de Biologia Evolutiva (CSIC-Univ. Pompeu Fabra)
Barcelona, Catalonia, Spain.

Buoyed by the Winds

The researchers assessed the viability of a transatlantic flight by analyzing the energy expenditure for the journey. They predicted that the flight over the ocean, lasting 5 to 8 days without stops, was feasible due to advantageous wind conditions. "The butterflies could only have completed this flight using a strategy alternating between active flight, which is costly energetically, and gliding the wind. We estimate that without wind, the butterflies could have flown a maximum of 780 km before consuming all their fat and, therefore, their energy," comments Eric Toro-Delgado, one of the article's co-authors.

The Saharan air layer is emphasized by researchers as a significant aerial route for dispersion. These wind currents are known to transport large amounts of Saharan dust from Africa to America, fertilizing the Amazon. This study now shows that these air currents are capable of transporting living organisms.

The Potential Impact of Migrations in the Context of Global Change

This finding indicates that natural aerial corridors connecting continents may exist, potentially facilitating the dispersal of species on a much larger scale than previously imagined.

I think this study does a good job of demonstrating how much we tend to underestimate the dispersal abilities of insects. Furthermore, it’s entirely possible that we are also underestimating the frequency of these types of dispersal events and their impact on ecosystems.

Dr. Megan Reich, co-author
Department of Biology
University of Ottawa, Ottawa, ON, Canada.

Throughout history, migratory phenomena have been important in defining species distributions as we observe them today.

Gerard Talavera, co-lead author
Institut Botànic de Barcelona (IBB)
CSIC-CMCNB, Barcelona, Catalonia, Spain
And Department of Organismic and Evolutionary Biology and Museum of Comparative Zoology
Harvard University, Cambridge, MA, USA.

Researchers emphasize that due to global warming and changing climate patterns, we may witness more notable changes and a potential increase in long-distance dispersal events. This could significantly impact biodiversity and ecosystems worldwide. “It is essential to promote systematic monitoring routines for dispersing insects, which could help predict and mitigate potential risks to biodiversity resulting from global change," concludes Gerard Talavera.

The incredible voyage of these animals was featured in the article titled "A trans-oceanic flight of over 4,200 km by painted lady butterflies" in Nature Communications Journal on June 25, 2024.

Abstract
The extent of aerial flows of insects circulating around the planet and their impact on ecosystems and biogeography remain enigmatic because of methodological challenges. Here we report a transatlantic crossing by Vanessa cardui butterflies spanning at least 4200 km, from West Africa to South America (French Guiana) and lasting between 5 and 8 days. Even more, we infer a likely natal origin for these individuals in Western Europe, and the journey Europe-Africa-South America could expand to 7000 km or more. This discovery was possible through an integrative approach, including coastal field surveys, wind trajectory modelling, genomics, pollen metabarcoding, ecological niche modelling, and multi-isotope geolocation of natal origins. The overall journey, which was energetically feasible only if assisted by winds, is among the longest documented for individual insects, and potentially the first verified transatlantic crossing. Our findings suggest that we may be underestimating transoceanic dispersal in insects and highlight the importance of aerial highways connecting continents by trade winds.

Introduction
Long-range insect migration has long fascinated scientists^1,2,3,4. Insects on the move are often observed far from their native range in open waters from ships at sea and from ocean platforms, on remote, unsuitable islands, or arriving along coastal beaches from trajectories that appear to stretch far out to sea^5,6,7,8,9,10. Despite decades of accumulated evidence, insect long-distance dispersal (LDD) nevertheless remains overlooked due to the dearth of reliable methods to track long-distance movements of such small and short-lived organisms. Miniaturized VHF radio transmitters have been successfully used to study the navigation ability of large insects overnight11 and radar tracking of insects is feasible over short distances^10,12,13. While promising, these technological advances limit dispersal records to short timescales (<day), sites with preexisting infrastructure (e.g., radars), and, due to body mass requirements, large insects. Consequently, they are not scalable to most migratory insects and sampling locations, potentially leading to an underestimation of the dispersal capacity of insects.

Here, we investigate a dispersal event by a flock of painted lady butterflies, Vanessa cardui, found on the Atlantic coast of South America (French Guiana), outside their native range. Three of about ten observed individuals were captured alive on the beach at ~6:00 am on the 28th of October 2013, apparently arriving after a vigorous flight across the ocean, judging from their damaged wings and resting behavior on the sand. Painted ladies are strong migrators, known for their recurrent trans-Saharan flights and a multigenerational cycle spanning ca. 15,000 km between the Afrotropical and the Palearctic regions^{14,15,16,17,18}. V. cardui is nearly cosmopolitan, but stable populations have not been recorded from South America. The individuals found on the coast of French Guiana should therefore have originated from populations in North America, Europe or Africa. Using an integrative approach that combines multiple sources of evidence, we show that the individuals found in South America migrated across the Atlantic Ocean from West Africa, with probable origins traced back to Europe. This journey encompassed a minimum flight distance of 4200 km over the ocean, and potentially exceeding 7000 km from the point of butterfly emergence.

Fig. 1: Wind backtracking suggests the transoceanic route followed by the painted lady butterflies.

Hourly backward wind trajectories for the 48 h prior to the butterfly flock observation at 6 am on October 28th, 2013. Trajectories were inferred by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) dispersion model⁶⁰, based on the Reanalysis database and computed on 200 h back trajectories for three different altitudinal layers (500 m, 1000 m and 2000 m.a.g.l.). Average altitude and speed ±SE along the course of the trajectories are represented for each altitudinal layer in the lower plots. Source Data can be obtained online using the provided code (see code availability).

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Fig. 2: Genome-wide phylogeographic assignments from SNPs obtained with a ddRAD sequencing approach demonstrate an Africa-Europe origin instead of a N. American one.

A Principal Component Analysis (PCA) using SNPs with less than 10% missing data per sample and pruned for LD (13 206 SNPs), the variances explained by the two first axes are 6.26% and 5.21%; B Co-ancestry matrix using fineRADstructure on a dataset of 7982 RAD loci. Both methods delimit two populations, one in North America and the other in Africa-Europe. Butterflies collected in French Guiana cluster with the Afro-European population. Source Data are provided as a Source Data file.

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Fig. 3: Metabarcoding of the pollen carried by the butterflies indicates the African origin of the transatlantic trip.

Classification of the obtained ITS2 metabarcoding sequences processed using a denoising pipeline (see Methods), and blasted on curated databases from A PLANiTS⁸³ and B Sickel et al.⁸² using the SINTAX classifier. In addition to plants present in French Guiana or widely distributed (green bars), two Sahelian endemic plants (yellow bars) were found among the pollen recovered from the bodies of the painted lady butterflies in South America: Guiera senegalensis and Ziziphus spina-christi, the former being especially common. Source Data is available in Supplementary Table S3.

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Fig. 4: Vanessa cardui transoceanic dispersers likely developed as larvae in Western Europe.

A Natal grounds inferred by a dual approach using δ²H and ⁸⁷Sr/⁸⁶Sr isotopes. Color scale depicts normalized joint probabilities by pixel. Assignments show high densities of high-probability pixels in America: Eastern North America, Venezuela, Brazil; Palearctic: Portugal, North Africa (mainly Tunisia and Libya), Saudi Arabia; Afrotropics: Mali, Nigeria, Chad and Congo. B Dual isotope assignments (in red, prob >0.5) overlaying with maps of highest probability breeding grounds for V. cardui inferred by Ecological Niche Modeling (ENM) for September and October (in gray, prob >0.7) in Southwest Palearctic and West Africa. Low suitability of reproductive habitat discards isotope-based predictions from North Africa, except a few pixels in coastal Morocco. C Infographic summarizing the possible natal grounds and dispersal pathway of a flock of V. cardui butterflies across the Atlantic from West Africa to South America, through a non-stop flight of a minimum of 4200 km during 5–8 days. The total flight distance for these individuals could be as long as 7000 km if they developed in Western Europe. Source Data can be obtained online using the provided code (see code availability). Butterfly illustrations by Blanca Martí.

Suchan, T., Bataille, C.P., Reich, M.S. et al.
A trans-oceanic flight of over 4,200 km by painted lady butterflies. Nat Commun 15, 5205 (2024). https://doi.org/10.1038/s41467-024-49079-2

Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

Possibly even more remarkable than the ability of these insects to undertake this long migratory flights, all for nothing, is the fact that there are still some people who attribute their abilities to the work of a supreme intelligence, when it make absolutely no sense to design something to do something so pointless.

Evolutionary speaking of course, the answer to this conundrum is to be found in the history of these butterflies when a different climate might have made these annual migrations make more sense in that they were a means of dispersal when populations built up and those that migrated north and back again successfully would have produced offspring with that ability and built-in genetic programming. In fact, the recent discovery that some of the offspring of the migrants do make it back to North Africa could be the reason this pattern of behaviour has not been filtered out by natural selection as the sedentary population is replenished each year by new migrants from the north.

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