Some sciences, like ecology, deal with relationships between things instead of objects. Groups as diverse as a biofilm, a biome, and a biosphere can qualify as ecosystems. Some sciences, like phenology (the subject of this article), deal with organisms’ responses to environmental cycles. 

In Current Biology, Kirsty H. Macphie and Albert B. Phillimore gave a primer on phenology. It’s an unfamiliar science, but one we all know by experience. Basically, it’s the Farmer’s Almanac with scientific rigor.

Flowers blooming, fungi fruiting, insects biting, fish spawning, geese migrating, deer calving; our consciousness is steeped in a seasonal calendar of nature’s events. Phenology is the study of these recurring, seasonal life-history events, though nowadays this term is widely applied to the events themselves. From Shakespeare’s sonnet 98, “From you I have been absent in the spring”, to the appearance of seasonal events and migratory species in the oral traditions of Native Americans, interest in phenology is long-standing and transcends cultures. [Emphasis added.]

Living on a Planet

The life we know survives not on a flat map, but on a globe, rotating daily, revolving around the sun annually. Our ever-cycling globe, with its grid of latitudes and longitudes, subjects organisms to periodic changes in living conditions, sometimes drastic. Added to those motions are the sun’s declination cycle (height above the horizon) and the phases of the moon. How do organisms respond? Do they migrate, like birds and eels? Do they shed their leaves, like deciduous trees? Do they change their clocks twice a year, like some unlucky humans? Let’s examine phenology, considering what insights it might contribute to intelligent design.

Phenology intersects with ecology by adding a time axis. Macphie and Phillimore explain:

Across the planet, certain times of the year are more favourable for life than others. Toward the poles we see this in the extreme, with a stark contrast between snow and ice and long nights in the winter versus warmer conditions and long days in the summer. Moving to temperate latitudes, the annual oscillation in temperature (Figure 1A) and the duration of daylight is pronounced but less extreme. Then, moving into the tropics, the major environmental axis of annual seasonality on land is between a wet and a dry season (Figure 1B), and day length varies much less, becoming invariant at the equator. Across ecosystems many primary producers time their emergence and growth to coincide with favourable abiotic conditions. This in turn has consequences that cascade from resource to consumer through food chains, with consumers timing their key life-history events, such as growth or breeding, to coincide with favourable abiotic conditions and often a seasonal peak in the availability of food.

While phenology is a fairly new science in formal terms, interest in the exact timing of seasonal change is as old as mankind. The Julian and Gregorian calendars are monuments to careful study of the equinoxes and solstices, both for farmers (to know when to plant crops) and for priests (to know when to plan religious holidays). For success, early phenologists observed biotic cues like the budding of trees and the return of birds, as well as abiotic cues like the rise of particular constellations or the alignment of shadows — Stonehenge and Chaco Canyon offering iconic examples.

Biotic and Abiotic Forces

A complete description of a species must factor in the time dimension. It’s not sufficient to describe a bird in springtime at noon; a full description of that bird’s anatomy and physiology must encompass diurnal/nocturnal and seasonal cycles as well as life history changes. A snowshoe hare will look like a different species in winter snow than it does in summer. Maple tree leaves undergo enormous seasonal changes. Annual migrating species like monarch butterflies and arctic terns spend much of their lives adjusting to seasonal changes. Others like sea turtles or Pacific salmon adjust their life histories to abiotic cycles, driven by the need to reproduce. Macphie and Phillimore focus on an even longer abiotic force: climate change. 

On that note, Robertson et al. in PNAS, after analyzing the migratory habits of  150 bird species over 20 years in relation to spring vegetation trends, theorized that “migrations of most species synchronize more closely with long-term averages of green-up timing than with current green-up conditions.” If so, this suggests that migrating species maintain a genetic memory of long-term averages. 

Predictable and Stochastic Forces

The success of a species depends on its adaptability to the abiotic forces that come with living on a spinning globe. Some of these are predictable to various degrees: insolation, daily temperature cycles, rainy seasons and dry seasons, high and low tides influenced by the sun and moon, and longer-term atmospheric and oceanic cycles like El Niño and La Niña. Due to the quasi-cyclic yet stochastic nature of atmospheric and marine currents, large variations are common for a given biome. Some abiotic events are completely unpredictable. These include earthquakes, wildfires, floods, or cyclones. The degree of internal resilience of an organism to sudden change will influence its ability to survive.

Accompanying the abiotic changes, biotic changes like locust plagues, mosquito swarms, pandemics, cicada emergences, ratios of predators and prey, and fluctuating pollinator abundances present challenges for organisms. Phenology therefore expands the suite of traits a species like a female migrating bird must possess today to fend itself from the slings and arrows of outrageous fortune it must face six months from now as well as when the time comes for egg-laying and incubating its young. Organisms must go with the flow and sometimes against it.

More Levels of Design Requirements

This means that over the history of life on earth, each surviving population has required more design specifications than it needed in ideal conditions. Intelligent design advocates see another example of foresight in the science of phenology. A black bear may feel comfortable in Alberta in summer, but what will its physiology and instincts require come winter? Those animal algorithms must be in place before the need arises.

Matching life events to abiotic cycles, furthermore, requires sensors to detect when changes are forthcoming. The authors say, “getting the timing right can matter greatly to an organism.” For example,

Consider a deciduous tree in a temperate forest: as spring arrives, the best time for leaf-out may arise as a trade-off between the benefits of leafing early, to maximise opportunities to take advantage of increasing light availability and warming temperature, and the benefits of leafing later, to minimise the risk of late frosts.

The timing of a tree’s leafing, in turn, influences the other organisms in its vicinity: availability of sunlight on the ground for herbaceous plants, or abundance of food for caterpillars. This interdependence is known as synchrony in the phenology lingo.

Equipment for Reading Cues

Every inhabitant of the globe must time its life history needs to the cycles around it. Successful timing involves the ability to sense cues and respond accordingly. Some cues come with clocklike or calendar precision, like sun angle and photoperiod.

Generally, however, the timing of favourable conditions will not occur on a fixed day of the year, and instead this timing may differ by a month or more from one year to the next. Therefore, many organisms use other information from their environment as supplemental or alternative phenological cues. In some cases, the environment may also act as a constraint on phenology.

Biosensors, therefore, must be capable of fine-tuning the predictable cycles by the unpredictable variations that modulate it. In the spring, temperatures and moisture levels in the soil trigger responses by seeds and shoots to generate flowers. Simultaneously, pollinating insects and birds are timing their hatchlings to the availability of nectar. Bears and squirrels in Canada have adjusted their emergence from hibernation to the arrival of spring temperatures. Examples are all around us:

There are cases where sea ice appears to act as a direct constraint on phenology, for instance, some colonies of polar seabird are unable to breed until the sea ice has melted, providing access to food. The timing of sea-ice melting has also been shown to influence the phenology of phytoplankton blooms and bowhead whale migration through the Bering Strait.

Where I live, the arrival of California poppy blooms can vary by a few weeks. Some will always appear, but the rare “superblooms” that carpet deserts with color follow complex algorithms of moisture, temperature, and competition that are still only poorly understood.

Is Phenology Darwinian?

The authors attempted to insert natural selection into the science of phenology:

Contemporary genetic adaptation in response to selection favouring individuals that are closer to the optimum timing provides a means of making up the shortfall between phenology and the optimum timing (Figure 3A). Consequently, phenological traits have attracted a lot of interest from evolutionary biologists working on global climate change. For an evolutionary response to occur, there must be a heritable component to phenology and there must be directional selection on phenology in response to the changing environment. From transplant experiments and resurrection studies on plant species (where seeds are stored and then plants are grown from seed at a later date), it is apparent that phenological traits can evolve very rapidly when placed under strong selection by shifts in temperature or drought.

Such an explanation, however, begs the question of whether heritable responses to timing are due to natural selection. They could be due to intrinsic programming for resilience. We note that the subjects of these experiments remain the same species, so not even microevolution has been demonstrated. The authors admit ignorance:

In comparison to plants and insects, the evidence for contemporary climate-mediated adaptive evolution of phenology in vertebrates is limited both in quantity and taxonomic breadth.

The only examples they present have the same problem: no new origin of species. They even used an example of artificial selection. This commits the faulty analogy Darwin used repeatedly, as documented in Robert Shedinger’s excellent book Darwin’s Bluff. The authors also point to examples of geographic dispersal as evidence for phenological evolution, but admit, 

Long-distance dispersals do occur in nature, and although it is clear that this could provide a source of genetic variation that enables a population to adapt to an earlier optimum phenology, the extent to which the direction of dispersal is adaptive or random is unclear.

In short, phenology does not support Darwinian evolution. Evolutionary biologists cannot point to heritable adaptations within species as support for the origin of species.

A Burgeoning Field

The burgeoning field of phenology, now growing explosively with the availability of big data sets and advances in monitoring technologies, offers opportunities for intelligent design advocates to assert the privileges of design thinking. One is the foresight required to equip an animal or plant for survival under sometimes drastic changes, some of them cyclic, and some unpredictable. Another advantage is the realization that organisms require additional design specifications, such as sensors, to monitor these cycles and be prepared for them. A third advantage is motivation to research the genetic basis of flexibility and resilience in the face of change. 

And finally, everyone thinking about how organisms thrive year-round on a spinning, dynamic globe can enjoy a quantum leap in awe. Animals and plants not only tolerate harsh conditions; they thrive in them, leveraging the slings and arrows of outrageous fortune into opportunities to grow and flourish. How is that possible without engineering for robustness? As we watch springtime animals and plants emerge from winter, we should ponder the built-in phenological mechanisms that make it possible.